We knew from the beginning we would likely rent DVC points for our honeymoon. Since our original date was 18 months away we were going to wait until the eleven month booking window to book the honeymoon; however, so certain family could attend we moved the wedding ahead by eleven months and wound up needing to book the honeymoon right away.
Edit: So I would say, as soon as you know where you want to honeymoon and when you want to honeymoon, book at the earliest opportunity possible.