It really depends on what was done as part of the winterization. I would talk to the dealer and find out exactly what items were done/completed as part of their winterization process.
If they did it correctly by the seadoo book, all you should need to do is put fresh gas in it, reconnect the battery and start it it up. I would probably replace the spark plugs after the first run out on the water. All the fogging oil gets burned up after the first start up and that can foul the plugs a bit, so it is best to replace spark plugs after the first run of the season. May also want to consider replacing the engine coolant if it has not been done in the last 2-3 years. It's and easy task to do yourself.
Congratulations on the new boat by the way! Post some pics...