I would guess Henderson gets a regular start. He last pitched on SEP 16, so he's on full 6 days rest.
He threw 95 pitches to get through 5 innings against the Cubs on SEP 9, then 87 pitches to get through 5 innings against the Pirates on SEP 16.
With the Phillies' lineup, running into deep counts might limit Henderson's innings due to pitch count. Probably a cap at 5 or 6 innings, but that's determined by number of pitches.