You should have time to get settled in at your resort prior to your ADR on your arrival day.
If this is your time at WDW, I would like to suggest that you purchase and read the "Unofficial Guide to WDW" ... it will give you a very good overview of the property and what to expect.
I would also suggest that you plan on having some downtime between park visits. The weather will be warm and it gets very exhausting for children and adults alike pounding the pavements, battling the crowds, and being exposed to every kind of stimuli known to man!!! LOL.
For the days you plan to visit the main parks, please try to be there early and then take a break mid-day when the crowds begin to build. Don't know how late you will want to be at the parks with the younger ones, but just be prepared to adjust your plans based on how everyone is doing. You can always plan another visit if you do not "see it all." In fact, plan on the fact that you will NOT do/see it all on this visit.
The UGW will help you to familiarize yourself with the parks ... you should then have the discussion with your children as to what their "must see" attractions are and make sure those get top priority. You certainly don't want to hear about "I didn't get to do what I wanted" on the trip home.
Enjoy, pace yourself, and do your homework PRIOR to arrival.