Five months seems like a long time.
When booking with airline points, I'll book 2-3 months in advance. (Because I have to.)
For package tours, I book as late as possible. Our kids play a lot of sports, and we usually don't know the schedules very far in advance.
I'm never worried about missing out on a particular hotel or even a particular country. There is always someplace else.
Once, I booked on a Tuesday to go to Italy that Friday. I came home with a guide to Tuscany and said to my wife, "Guess what?". I'm lucky --- she likes to travel but isn't interested in any of the planning.