Henne had a ~85 QB rating in the final 8 games, scoring ~20 points per game and the team finished with a 4-4 record.    It's not unreasonable to expect an 8-8 caliber team when he has a full year under the offsense, with young talent continuing their upward career arc, significant and badly needed upgrades at RB, DL, SLB, OG and WR added in the offseason and a much easier schedule substituting the AFC and NFC West with the NFC East and AFC North.   The team can then swing +/- 2 games based on luck either way.  Every year some unknown team takes a 6-8 game swing by simply playing solid defense and special teams, efficiently throwing the ball, shortening the game through a running attack and winning the turnover margin .  Last year it was the Chiefs.  The year before the Vikings.    Heck, Parcells first year in Dallas in 2003 he went 10-6 with Quincy Carter as the QB and Troy Hambrick as the feature RB.  

 

That said, 10-6 is probably your franchise ceiling under Henne, so the answer to the original question of the thread is that Bortles starts as soon as he's deemed ready to do so, regardless of what Henne does or doesn't do. 

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