Starting my question as a new thread as others could benefit from this information. How early should we be at the airport to catch flights between islands - i.e.: Athens to Crete and Naxos to Athens? We all have backpacks, no large luggage, but the one backpack would have to be checked.
About the same as usual. Good hour to hour and a half. You still have the usual procedures to do through via security checks, etc. The island airports are smaller with fewer flights and people but still takes time. However, Athens is big airport so I would plan two hours.
15:30 is plenty of time for that flight to Crete ... 1.5 hours.... there are only 35-40 people to check thru. And in Naxos, 1 hour.
Assuming you're flying Aegean/Olympic Air to Crete you can print out your boarding passes 48 hours in advance. If you can do this it will take you less time in Athens since you will only have to take your bags to a specially designated drop-off point as you enter the departure zone. And because Naxos>Athens is on a smaller plane with no other planes waiting to take off an hour is plenty.