Not only dont bother with Blue Hole, but I would suggest that you make one of your dives at Hol Chan.

Even though this is only a 10-25 ft dive, you will see more marine life there than anywhere else ....and it takes a little more co ordination to hover at 15' than at 80', so you will have to work on buoyancy control, which is a good exercise.

Also remember no dives for 24 hours before you flight home (from BZE that is, the San Pedro -BZE flight is all below 1500 feet)

Enjoy

It's rarely rocket science, it's usually just math: then again if you can't do the math.......