Overplanning - is it okay to wait

I am booked on my first RC cruise next December. I have been on many previous cruises with Carnival, Celebrity and NCL. We are on the Grandeur over Christmas / New Years and I am just browsing over the excursions and packages available. I know the Holiday itinerary may reduce any deals available but I like to shop! My concern is that there is a zip lining excursion in St. Kitts that we have done before and loved. It is available through the ship which according to the company means it cannot be booked independently and it will likely sell out. Our port day at this point looks like the Allure (5400passengers) and MSC Fantasia (4000passengers) will be joining us. One concern is that Allure will have the same excursion choices and with this many people in port - it may get sold out. I cannot rationalize reserving and paying this far in advance (my husband already thinks I am nuts) but when is it realistic to reserve an excursion. If we were to cancel the cruise, I assume those expenses are refundable. I also have the same question about the internet and beverage package promotions - any experience as to a reasonable expectation to book these knowing what the cycle of promotion. Planning is part of the fun but I also tend to overthink!

You are correct, if you cancel the cruise, excursions, dining, spa treatments, etc., are automatically refunded to the same credit card used to book them.

I would get a good idea of what you want to do. Keep an eye on what you want to buy and when it goes on sale purchase it. If you wait til last minute you are most likely to pay more.