The more notice, the better. Going forward, make the request as soon as soon as you know your desired dates. As others have said, it's largely dependent on the client and their schedule and what your responsibilities are. A situation where you have 10 consultants on a project with a year-out deadline may be very difference than one where there are 2 consultants and the client always needs one of them to be on call or on site.

That said, if they've told you that you get a week to use by year end, then November isn't too early to be taking time off, and if you're just looking for 3 days M-W to make that a full week off, that's a very normal and reasonable vacation request.

I'd ask the recruiter what they suggest. Find out who will approve the request, and when you can put it in.