IF it wasn't renewed, drops will likely happen on the 76th day after expiration. That is also IF nobody bid on it at SnapNames.com already etc. 70-71 days After the expire date, I would be checking SnapNames or any drop site to see if it's listed in Pending Delete status.
You can also do a scan using DRT of Today's Pending Delete domain names and see the dates for the domains that are dropping today from Dotster which would help guide you Stu.