Charter booking times

In forum users experience, is there any advantage to booking months ahead of time as far as charter rates are concerned? Or are last minute rates cheaper.

It really depends on the company and season. One company was very cash poor for a while and was making phenomenal last minute deals. Rates with almost any company can have some negotiation room. Don't be afraid to ask for a free sleepaboard to close a deal as a example. 10 for 7 in the low season is also common. Some companies mail out specials if you are a repeat customer. Almost all companies offer a repeat charter discount.
If you are looking to book for this June I would get it done ASAP as last June the Moorings was completely out of 4 cabin boats and had no 3 cabin boats with AC. I suspect the same was true at most companies.
G

The biggest advantage of booking months in advance is that you get your dates and the boat you want. This is important for school holidays if you have children, or other restrictions. Then you can tract airline prices and lock in at a rate you are happy with. Wait too late and airlines fill up/ prices increase.

As an owner, I offer discounts months in advance. I also offer additional savings for "last minute" bookings. Generally 2 months in advance. For example, I have 2 weeks in June /July that would get a 35% discount.