After they expire, domains take 75 days to become available.

During the first 61 days the domains' status is: PENDING DELETE RESTORABLE
During the last two weeks, their status is: PENDING DELETE SCHEDULED FOR RELEASE

The domains are released at 9 pm UTC / GMT.

In other locations the time is:
1.30 am Mumbai and New Delhi
4 pm U.S. Eastern
1 pm U.S. Pacific