While the Eagles have not released a timeline for Peters recovery, it is typically seen as a 9-12 month process for this type of injury. So whole there is a chance he could maybe return late this season, it doesn't seem terribly likely. However, given that this happened when it did, he should be ready to go for the 2013 season.
By that time, he'll not only have been through the full 12 months, but also have an extra 5 months or so of recovery time before that season starts. So really, if they expect him back after one season, there would really be no need to use a first round pick on the OT position as some have suggested.