Per PUP rules...
The earliest Lewis can return to practice: Monday, October 17
The latest Lewis can begin practicing: Tuesday, November 22
The earliest Lewis can make his 2016 debut: Week 7 versus Pittsburgh
The latest Lewis can make his 2016 debut: Week 14 versus Baltimore
Once a PUP player begins practicing, he can remain on the PUP list for a period not exceeding 21 calendar days. So if Lewis practices on Nov. 22, the latest he can be activated is Monday, December 12, when the Pats host the Ravens on Monday Night Football.
As steady as James White has been, Lewis obviously adds a new dimension to the Patriots offense, which already has a
nice stable of playmakers in Rob Gronkowski, Julian Edelman, Martellus Bennett, White, Chris Hogan, and Danny Amendola.
As we saw with Gronkowski's hamstring issue, the Patriots will be patient in bringing back injured players, especially if they continue to cruise through the regular season.
While it's impossible to predict injuries, the Pats want to give themselves the best chance to be healthy heading into the playoffs. They certainly do not want a repeat of 2015, when the league's best team was wrecked by injuries late in the year.
For this reason, it wouldn't be a surprise to see the Patriots proceed cautiously with Lewis.
http://blog.masslive.com/patriots/2016/10/dion_lewis_injury_update_new_e.html#incart_river_index