Very wise. I tend to check in an hour before departure and get enough time to have a light meal within that timetable. Salad and cheesecake sort of thing. Now I probably rush it a bit, not wishing to spend my entire life in an airport, so if you give it 90 to 120 minutes, you could have ample time to slowly work your way through it. There's another good reason for planning on being full an hour before departure - by the time you are airborne you will feel quite full and perhaps a bit dozy with it. My trick is to practice how to kick the foolstool down whilst seat-belted on the ground. Get you duvet in the right position too. That way you can get your bed set up 5 minutes after take-off, and ideally asleep in 10 minutes.