There are no requirments to diving immediatley after flying and this is possible, but as others have indicated it is not really feasible upon arrival on Ambergris.
If you arrive on the Taca flight which lands in belize at 9.30am you would be on island in time for the 2pm dive departure, other than that it would not work.
Flying after diving is another matter though and the Flying after diving procedures are as follows (they change frequently so chekc with Padi for confirmation)
Any day of diving within normal diving limits WAIT 12 HOURS (I still suggest 24 hours but 12 is the number the agencies give)
Any consecutive day of diving meaning more than 1 ie 2,3, or 4 days diving(WAIT 24HRS)
As an instructor it is my opinion that a good 24hrs is always a good safety idea.
After working in the chamber a few years ago the biggest problem I saw was dehydration which caused 95% of diving problems, keep this in mind and ensure you drink plenty of water and non citric juices such as apple and melon.
The water here is not enough on its own and not many people know this but it is reverse osmosis desalinated purified water and not good at replenishing the lost salts and minerals lost due to sweat.
What this means is it has absolutely no minerals or electrolytes in it whatsover and is really useless for rehydrating and replenishing lost salts due to persperation etc, therefore it has to be supplemented with Gatorade or another Juice.
A good rule of thumb when diving to see if you are dehydrated is the following
When you go to the bathroom to pee pee if its anything other than clear like water you are dehydrated and need to drink more fluids.
All the best
Playa Blanca Beach Resort www.divebelize.com