Amid the challenges, more than half of employees say they’re “excited” or “happy” to be heading back to work, according to a survey of 1,000 full-time U.S. workers by Workhuman exclusively for Fortune. A smaller number were unhappy, however, with nearly 15% saying they’re anxious and about 8% saying return-to-work plans are causing stress.

Of course, many companies are already requiring employees to work in person after months of doing so remotely during the pandemic. Other businesses —particularly those in retail and health and food services—never switched.

But the spread of the new Omicron variant is causing some major corporations to rethink their return-to-office dates that they had set a few months ago when COVID infection rates were declining. Last week, Google announced it would not require employees to return to the office on Jan. 10, 2022, as it had previously planned. Meanwhile Meta, Facebook’s parent company, said Wednesday that while it was still planning to reopen offices on Jan. 31, employees could defer returning for up to five months.

In many cases, U.S. workers have already started returning on a voluntary basis. The survey, conducted the week of Dec. 6, found that about 83% of workers say they’ve visited the office at least once in the past month. Only 17% have remained fully remote. 

Yet the return to the office is not without its challenges—and most employees say they need advanced notice from their companies in order to prepare for working on-site again. Roughly four out of 10 employees say they need their companies to give them a week's notice, while 20% say they’d need closer to a month to make the necessary arrangements. 

That advance notice may be more necessary because many of the workers planning to return to the office in January say they likely won’t be taking advantage of hybrid work. About 40% anticipate being in the office five days a week.