Generally about a month ahead, but there are some variables.
If you used a TA, the TA can specify whether the documents should be sent to them first or directly to you. The theory is that they will check the docs and make sure that everything is correct. Obviously, if they go to the TA first, there will be a few days of delay before you get them.
Also, if you buy air thru
DCL, they tend to come a little later than if you booked only the cruise--like 3 weeks ahead.
There is NOTHING in the documents that you need. Everything is available on line. The luggage tags are the one useful thing, but if for some reason you don't get the docs, you can get replacement luggage tags at the Welcome Center at MCO (lower level, terminal B), at the cruise desk at any WDW resort, or at the terminal from the porters who take your luggage (if using private transportation.) There is essentially no way to get on a cruise out of Florida without going to one of these places along the way!
