Apple will begin phasing in its planned hybrid work pilot on April 11th, bringing employees back to the office one day a week to start, according to an email from CEO Tim Cook to Apple employees, which was seen by The Verge. Apple originally announced its plans for a hybrid work pilot in November.

In the third week of the pilot, Cook writes, employees will come in twice a week, with the full hybrid pilot — where workers will come into the office on Monday, Tuesday, and Thursday and work “flexibly” on Wednesday and Friday — would go into effect May 23rd. The timing may vary from office to office depending on local conditions, Cook added.

“For many of you, I know that returning to the office represents a long-awaited milestone and a positive sign that we can engage more fully with the colleagues who play such an important role in our lives,” he wrote. “For others, it may also be an unsettling change. I want you to know that we are deeply committed to giving you the support and flexibility that you need in this next phase.” He added that the hybrid plan includes an option to work remotely for up to four weeks a year.

“As we begin this pilot, we are looking forward to learning as we go and adjusting where we need to, all in service of fostering a really collaborative and flexible approach to our work together,” Cook wrote. “In the coming weeks and months, we have an opportunity to combine the best of what we have learned about working remotely with the irreplaceable benefits of in-person collaboration.”

Cook also said in the email that Apple’s retail stores will revert to being mask-optional “over the next few weeks.”

Apple has changed the return-to-office date several times amid the ebb and flow of coronavirus cases and restrictions; most recently, Apple “indefinitely delayed” the office return, which had been scheduled for February 1st. It’s also begun dropping mask requirements for Apple retail customers in some areas.

Apple didn’t immediately reply to a request for comment from The Verge on Friday.

The full text of Cook’s email is below:

Zoë Schiffer contributed reporting