I agree with wheelhouse's starting points. Stuff you can't do in the water like bottom paint, seackocks, rudder bushings (http://www.drmarine.com/),
check the cutlass bearing, shaft log, stuffing box (at the very least find out what you will use to tighten this before you launch), and engine work is usually easier on the hard.
Next, think of things you can't do after the rig is up like chainplates, standing rigging, mast wiring for lights/VHF/insturments. Once you're floating with the rig up - well everything pretty muchs stops then and you go sailing.
Congrats on the boat, guarantee you're gonna love it.