We're going in mid-May and really just started planning 2 weeks ago so I don't think it's too late. Would highly suggest looking at some of the offers available thru Disney now -- and also comparing what you need to the special deals. We're going to be at WDW for a week, but only still need reservations for 2 nights (have booked the other ressie). If we book a package for 2 nights and the upgraded tickets for 8 days it's about $1500, however if we book for 3 nights and the same tickets it's only $973 !!!
I realize that makes no economic sense, but I ain't complaining !! They have a Toddler/Pre-schooler package for 2 adults 1 toddler that requires a 3 night minimum which is cheaper (by about $500) than staying for only 2 nights, so I guess we'll stay 1 more night and get paid about $500 to do it !! Point is depending on the length of your trip and the deals available you may be better off booking the "deal" for 5 days even if you're only going to be there for 4.
Good luck -- see ya there !!