If it's your first time please get a guide. They will show you around and teach you tips and tricks that will save you time and energy. They will also show you how to use your avalanche gear even though they most likely won't take you in avalanche terrain. Mountain snowmobiling is exhausting and way worse if you don't know what you are doing.
If you get a a guide day 1 then you can go out day 2 and 3 and know safe areas. I would probably ride 1-2 days then have a rest day and then ride another. There are plenty of places I ride where is "safe during high avalanche danger". However one wrong turn or thinking you can take a short cut to get there can get you in a very dangerous spot.
Snow machining is great. It blows my mind though that people actually enjoy riding around on groomed trails. Ive never done that, it would be really boring.