I didn't see what group this was in, I usually fly from BKK, but as I said somewhere else it's worth spending 2 nights, arriving late the first night and getting up nice and early the next day!
Ahhh. In that case I'd suggest just arriving 3.30, book into a hotel, get to embassy nice and early the next day, pick up visa the day after and fly back.
They actually give out the visas in the same order that they are applied for from the day before so the earlier you arrive on the first day, the earlier you get out the day of pickup.