For us, it "depends".
Non revenue, first flight of the tour, 1.5 hours.
Revenue, first flight of the tour, 2 hours.
Tricky locations, add 15+ minutes etc.
Only time we're 4-5 hours early is if there's been a change and couldn't change our show time and they've tacked a hotspare duty on before flying...
We rarely use the public terminal, if we do our handling agent hands us the small to large tree of paper and we're escorted through security and immigration (if required).
Non airline operations.