fed planner

Here's a question I was going to ask in a separate thread but this question is related.

Planning a Med Cruise next June and need three tickets (in business). I will only have enough miles for one ticket, maybe two (but not right away). What is best approach to do this? Should I book one way awards when they open, them either book the return when that opens or should we pay miles one way and $ the other (at least one ticket will be bought outright - and I would like to wait for a potential sell). But I feel we need to get the miles ticket booked early.

Anyone have any experience or advise?

Thanks.