No issue leaving the airport after you've checked in and dropped your bags - but I am not sure check-in / bag drop will be open that early? Certainly not for the 208 and I can't recall what time the earlier flight leaves ie whether the desks might be manned at that time for the 206 or whatever it is.

Going airside first and then landside achieves nothing so I wouldn't do that unless you have a specific reason for that sort of movement around.