I wouldn't wait until the spring to change your oil ... especially on a new ski. There's a reason BRP tells you to do it post season ... not pre season. Any contamination (including water) that is in the oil will remain in the engine over the winter (off season storage). That can cause internal corrosion, and rapid wear of very expensive engine components the next time you start it up. I have always followed the BRP off season storage instructions to the letter, and my 16 year old skis fire right up in the spring, and they run great all season. Shortcuts can be expensive!
It's not just your spark plugs ... you have to remove your fuel injectors too. The spark plug boss gets the lubricant in the combustion chamber pistons, rings, cylinders, and the injectors allow you to get the lubricant (Fogging oil) on the intake valves.
If you are in a very cold climate where you will have temps below freezing, it's also a good idea to pull the impeller cover (3 bolts) to see if there is any water in the jet pump bearing cavity. I have read posts from folks up north who find cracked pumps in the spring time.
Spend some time reading your shop manual. It will pay off in the long run.
Also, get one of these for your oil changes. Pumping the oil out take a while.
https://www.amazon.com/gp/product/B01KZIFZVK/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1