When does UA typically finalize (late) summer schedules?

I'm trying to fly SFO-FCA (Glacier) the Thu before Labor Day and the ticket prices are unsurprisingly astronomical. Was thinking I'd book one for Wed and try to hope for a schedule change, but I want to balance "time for a schedule change" with "time I'll have to use the credit if I end up canceling".

Edit: I suppose if the booking is speculative anyway I might as well book one with connections to give myself more chances at a schedule change.