(CNN) -- Ideally, Casey St. Clair would be spending Thanksgiving relaxing and eating dinner with her boyfriend and his family. Instead, the part-time Target employee and substitute teacher will work Thursday night during the early kickoff of the big-box retailer's Black Friday sale. Stores will open at 9 p.m. on Thanksgiving this year, reflecting a wider shift in the retail industry toward getting a head start on the biggest shopping day of the year.
As it stands now, Toys R Us, Wal-Mart, Sears and KMart will be the first large retail chains to open their doors for bargain hunters at 8 p.m. Many other chains are open Thanksgiving Day, but their Black Friday sales don't start until midnight or Friday morning.
St. Clair, who lives in Corona, California, is scheduled to work Wednesday from 7 p.m. to 3 a.m. She'll return Thanksgiving Day before 9 p.m. and work until 5:15 on Friday morning. She has to sleep at some point, so family dinner is out.
She likes working for Target, which is why she has stayed with the company for six years, even after relocating from the East Coast in 2011, she said.
St. Clair's also grateful to have a job that pays time and a half plus bonus pay for overnight hours, even if it means she can't fly home to her own family for the holidays.
But after watching Black Friday sales start earlier each year, she decided the company had gone too far this time and started a Change.org petition asking Target CEO Gregg W. Steinhafel to forgo the plan to open stores on Thanksgiving.
"I wasn't too happy about going in at midnight last year, but when I found out we were starting on Thanksgiving night this year, I thought enough is enough," St. Clair said in a phone interview. "It's one of few days retail employees get to spend with their families, but at this point there's no time to see family."
She's not the only one who thinks the "Black Friday creep" hurts employees and their families.
More than 40 petitions have been launched on Change.org asking retailers including Sears, Target, Walmart and Kohl's to "give Thanksgiving back to families." Many of them popped up after St. Clair's appeared Friday, earning more than 200,000 signatures as of Wednesday.
When it started earning traction, Change.org promoted the petition among users, but even before then it had taken on a life of its own, site spokeswoman Charlotte Hill said.
"Employees and customers alike are saying, 'Thanksgiving should be about celebrating with family, not shopping for the latest deals,' " Hill said.
Comments on the petitions echo that sentiment, with some threatening to boycott stores that they say put revenue before employees.
"I'm a conscious consumer; I think of good reasons to shop where I do, and consider why and why not to give any store my money. Seeing this happen year after year to the employees of Target irks me, and makes me want to ... take my money elsewhere," one user said.
Other comments in petitions against Target and other retailers focused on the importance of letting employees spend time with family.
"After 33 years in retail, I still love everything about the holidays....except telling some poor employee she has to forgo her family holiday because she has to work! We really have to put a limit on the madness!" said a person who signed a petition titled, "Retailers: Stop Black Thursday."
"Families should come before retail sales! Give these people the day off that they deserve," said another person who signed the petition "Wal-Mart: Move Black Friday Start Back to Friday."
Relatives of retail employees are also speaking out. The sister of a Target employee in Illinois started a petition on behalf of her family, claiming that for them, Thanksgiving will "not be complete" without him.
"Family has always been important to me and Thanksgiving is all about family," Jennifer Ann said in her petition, "Target: Don't take away Thanksgiving." She asked to withhold her last name in deference to her brother, who asked to conceal his identity.
Last year, it was hard for her 24-year-old brother, who has worked for Target since high school, to relax knowing he had to be at work, she said in an interview with sister network HLN. He rushed through dinner and had to leave for his shift just as everyone was starting to unwind.
This year, he's going to miss dinner altogether, she said.
"It's just unfortunate that he has to be at work when we're celebrating," she said. "I get that you sign up for things like this. (But) you don't typically have to work on Thanksgiving when you work in retail, and this is something that's kind of gradually happened."
Target and other big-box retailers say they're responding to consumer demands as best they can -- with employees in mind.
"Target's opening time was carefully evaluated with our guests, team and the business in mind. Across the country, team member preferences were considered in creating our store staffing schedules," said spokeswoman Molly Snyder. "Thanksgiving weekend is one of the busiest of the year, and we appreciate our Target team's flexibility on this weekend and throughout the holiday season."
All hourly employees who work on a national holiday, including Thanksgiving, receive pay equal to time and a half their hourly pay rate, she said. Additionally, team members who work certain hours on Thanksgiving and Friday will receive shift differential pay and holiday premium pay.
Walmart also was named in several petitions, though most of its stores are open 24 hours and 365 days a year, including Thanksgiving. Last year, customer traffic was highest during the 10 p.m. hour on Thanksgiving, a spokesman said
"We appreciate our associates for everything they do to serve our customers during this busy shopping season and every day throughout the year," spokesman Steve Restivo said in an e-mail. "According to the National Retail Federation, Thanksgiving night shopping has surged over the past three years. Most of our stores are open 24 hours and, historically, much of our Black Friday preparations have been done on Thanksgiving, which is not unusual in the retail industry."
Ultimately, the power is in the hands of consumers to drive down the demand for extended shopping hours, retail and employment experts agreed.
Labor Day and Memorial Day used to be days of rest, too, said Rich Milgram, CEO of career network Beyond.com, which connects employers and job seekers. But now, sales on those days are the norm, showing that over time, society grows accustomed to changes and demands of the free market.
"This says less about the retailer and more about society as a whole. Target, Sears, Kmart and others are all doing what they need to do maximize sales and profits," he said.
Just as consumers are driving the demand, employees are choosing to work in the field, leaving companies with little choice but to take advantage of every opportunity in the marketplace, said Bill Peppler with staffing firm Kavaliro.
"In today's economy where jobs are scarce and unemployment is high, people are willing to do more now than they were willing to do two to three years ago. This is especially true in retail. Black Friday alone last year led to almost $12 billion in sales, so you can understand the employers stance on this issue," he said.
Does this mean that Christmas and New Years shopping is next?
Probably not, said Brooks Holtom, associate professor of management at Georgetown University's McDonough School of Business.
"I would suggest they are much less at risk because most of the shopping we see at Thanksgiving is in anticipation of Christmas. The incentive for retailers to open on Christmas and New Year's is much lower."
St. Clair knows it's too late to realistically expect Target to change its tune this year. But she is hopeful that her petition and others like it will make Target's leadership reconsider opening early for Thanksgiving next year.
"Going forward I hope it forces Target and other companies to take another look when they realize how many people out there care about this issue," she said.
Until then, St. Clair plans to be in the electronics section Thanksgiving night through the morning hours of Black Friday.
"I do value my job and that's my schedule," she said. "I will definitely honor that, as much as I don't agree with it."