You'll be fine-- I have been to WDW on a family trip 2 times and am going in April again. Both of times I went there completely unprepared.. no planning, was not even AWARE of 1/3 of the things you can do in the parks, not to mention the rest of the property. I didn't realise what I was getting into and didnt even know to plan. We go to amusement parks all the time and other then making our reservations, never really put much thought or effort into, so I just assumed a trip to WDW was the same. Looking back, we missed a lot of stuff just from lack of knowledge but we had a fantastic time both trips. Both times we came home & said.. wow, that was the best vacation ever!
With that said, our next trip is in 44 days and I am a lot better prepared. I have been reading every WDW book I can get my hands on, spent HOURS on this and other Boards, reading, questioning, posting, and other then some ADR's and knowing which parks we "plan" to do each day, that's pretty much it. I spent some time with each DS going through the rides, shows, etc and let each of them pick 10 rides/shows (total combined from all parks) that they just HAVE to do. -- lucky for us most of their choices overlapped, so we have a list of 22 things we HAVE to for the boys, and DH & I total. and we have 8 days to do them in. Hopefully, we are able to do all 22 and then tons more, but if not, we'll still have time together as a family making memories.
Having done Dinsney w/o plans before and now going there with "tenative" plans, I'm anxious to see the difference in the vacations. I understand that these trips are expensive for most of the people who take them, and most of us are not fortunate enough to go multiple times a year or even once a year as a result, we all want the trip to be "Perfect". Just don't forget that a perfect trip will still have snags...I will say that I am not going to be so caught up in the plans that I miss the moments.
You are well prepared. Now is the time to RELAX and ENJOY the results of your prep work.