No, you aren't charged until you board. I don't know if you can book prior to 60 days out but I doubt it. You have up until 2 days to cancel an excursion should you change your mind. This is a nice point of flexibility. If you call and can't get the excursion you want (some have limited space) see if you can get wait listed or just check back every once and awhile, even while on board. We did the Kayak tour in Freeport (first time kayaking outside the US and it was AMAZING! OK, our guides were hysterical which made it even better!) and several people signed up the night before.