The expectation is that he won't be ready for the Sept. 8 opener against the Bills, or for the quick turnaround against the Jets on Thursday, Sept. 12.
Then it lines up this way:
Sept. 22: vs. Buccaneers
Sept. 29: at Falcons
Oct. 6: at Bengals
Oct. 13: vs. Saints
Sometime within that range looks like the sweet spot for when Gronkowski might be ready to deliver one of his "boom" touchdown spikes. The Patriots almost certainly would have placed him on the reserve/physically unable to perform list if that were not a realistic expectation.
The Boston Herald is reporting Monday that Gronk was in 11-on-11 drills and is hearing whispers that a Week 2 return is possible, which is a Thursday night. The Week 3 or 4 reports fall in line with what we've been hearing the most. Any time after the above dates and the team likely would have put Gronk on the PUP list. All things considered, it certainly seems like Gronk will return sooner than later, making those who took a shot on him in drafts very happy. If you haven't drafted yet, the safest spot is still round 3 or 4, but you should also get a capable backup.