Glad to see a supportive mother! Gay Days is a ton of fun and I'm sure your son would love it.
Gay Days releases a schedule for their "red shirt days." Each of the 4 Disney World parks has a different day where you can wear a red shirt and pride gear. I don't think the schedule for next year has been released yet, but the park days are generally Thurs - Sun. The Magic Kingdom day almost always falls on the Saturday, and is by far the most attended. It's cool to see so many lgbt people and families in the park with a sea of fun red shirts, and it leads to a very social atmosphere.
It may take a bit for the schedule to be released for 2021 (this June's gay days was rescheduled to October b/c of the pandemic, so that is the only schedule available right now). This year's days were: Thursday - Animal Kingdom, Friday - Hollywood Studios, Saturday - Magic Kingdom, Sunday - EPCOT.
You should decide whether you want to link up with the red shirt days for all park days or just some of them, and then you can start planning which days you'll do which park and what dining options you want to hit for advance reservations. If you only do one red shirt day, please make it Magic Kingdom! Again, it's the most well attended and is a very joyous day that your son will love.
If it has been a while since your last trip, I encourage you to check out the many trip planning forums here on dining and fast pass reservations. Folks have been very thorough and detailed in documenting everything you need to know.