Hi Jennifer,
Good for you to be planning now...and no, it is not too early! Here is why:
1) By booking early, you will most likely get the resort and type of accommodation you want. November (around Thanksgiving) and from mid-December on are peak season. Book early to ensure you get the accommodation you want. If a special comes out, the cast members at reservations (407-WDISNEY) can modify your existing reservation to give you the better deal! I highly recommend this. Keep watching this webpage which will tell you about
upcoming specials.
2) You will have an advantage if you want to make character dining or special restaurant reservations. These meal sell out early, so make sure to book that exactly 180 days in advance of the date you want it - just call 407-WDW-DINE.
3) Planning early will help you decide what you want included in your vacation. So when you do see a special, you can call quickly and know exactly what to ask for. Evaluate now if you will want the dining plan, park tickets (base ticket? hopper pass? want to include waterparks?) and so on. A deal is not as much of a deal if it includes things you do not want or need.
Regarding specials you have seen, based on a family of 4: I have seen this too in ads where they quote a price, based on a family of four. My advice is when you see a special, call the reservations line and give them the specifics of what you want to book. They will quote you based on 2 adults and a 3 year old.
Jennifer, have a wonderful family time together!