I’ve done this before for a couple of cruises. I didn’t pick a cruise within the 90 days. I still received the on board credit and my deposits. But I don’t think I’ll do it in the future unless I know what cruise I want to book. In order to book some outside insurance, you need to do so within a certain number of days after the booking date. The day you pay your deposit is the booking date. You also can’t transfer the booking to a travel agent after 30 days.