When the gang first moved out of the Grizzlies Dutch sent Micah and Lenny out to scout ahead, after the start of Chapter 2 you can always see them briefly at camp, it’s unique dialogue with Arthur asking them it it were any trouble, both of them saying it was nothing to worry about. (this dialogue may only trigger in 1.00)

*Fast forward to Exit Pursued by a Bruised Ego*

When you reach the Grizzlies East you have a option to talk about either Sean or Micah. If you choose Micah, Arthur will ponder about his and Lenny’s whereabouts, about how it haven’t been that long since Ms. Grimshaw sent them out to scout ahead.

So first Dutch sent them to just scout ahead on the trail, then when they briefly returned back at camp, at some point Susan requested for them to go out scouting again.

Which means they never went to Strawberry right away, only when Hosea and Arthur went off hunting or even before that I could be wrong

I believe Micah took the second scouting trip as a opportunity to tie up loose ends and pay a couple of social calls, and just dragged Lenny along like anyone else.