In my experience, book way early or book last minute. The in-betweens are the worst.
If your heart is set on going on that cruise on that date, just book it. If you're more flexible, wait and see what last-minute specials pop up. They're usually fantastic if you don't care what room you're in, but you also risk NO last-minute special if the cruise sells out, or something inside if you wanted outside.
Also, having looked at last-minute specials, the older ships have them more than the newer ships. So the Legend might fill up, leaving you nothing to book.
So, if that wasn't clear as mud, if you want that ship in that month with that destination, book it now. If you just want to cruise in the summer, wait and find some specials.
as Denise stated depending upon what you want you can go either way. If you want a particular ship, particular date and particular cabin category i would book it now. If you are flexible and can go last minute and don't care where you go or what type of cabin you get then wait and watch. Better yet, call a travel agent in your area and see what she can do for you, most agents will meet or beat most offers posted on the web. I like to book eary to get the exact cabin that i want. If you aren't particular about a specific cabin but know what cabin class you want, you can book a cabin guarantee-- that means you will get a cabin in that cabin class - nothing less, but it might give you a fair chance of an upgrade.
YOU CAN FLY TO FLORIDA AND CRUISE FOR ABOUT THE SAME PRICE AS CRUISING FROM NEW YORK. THERE ARE STILL PLENTY OF CABINS FROM FLORIDA. YOU DO NOT WANT A CRUISE THAT IS OVERLOADED WITH KIDS. I HAVE HEARD SOME REAL HORROR STORIES LATELY SO DO YOUR HOMEWORK!!!
I'm booked for Legend, Oct 04 out of NYC. Lots of cruises are cheaper from FL, but maybe not $200 per person cheaper (which is what you'll pay for air from NY). Also, the Legend cruise is 8 nights instead of 7nights (as most other cruises are). The summer is most expensive on the Legend, you might want to look at late september & october. I used cruisequick.com and they found me an incredible price (I was even able to afford a balcony!).
Let me know if you book on Legend or if you have questions about the ship (I've done so much research on this ship, I could tell you almost anything!!)