Your timing seems right. Magic Kingdom will require the most time.
We RD’d and took mid-day breaks as suggested and we were so glad we did. You can get so much done in MK the first hour with no wait it is worth getting there early. By 11am we had 8 attractions complete with no wait. Don’t underestimate the productivity and time saving of RD. My family is so sold on this touring style now.
On our last day at MK we decided to arrive a bit latter as we had completed all attractions the previous 2 MK days and it was a “favourites” day. It was a gong show. 30 minutes later arrival equated an eternity to enter the park. This was parking at 830 wait for tram, long wait at security and then stuffed into ferry or monorail, and more wait at tapstiles. We entered main street a good hour after arriving at the lot. This was a CL 7 day.
Arriving an hour/45 before RD at MK is a big advantage. I would think the higher volume arrival crowds would be consistent through at least 1030. I would consider RD MK days at least and more leisurely mornings at other parks.
As for the other parks RD might not be as important and less hassle getting in the gates than MK, however it will be busy for the first hour or so at the trams at all parks. If you have any desire to ride FOP at AK and don’t have a FP then at tapstiles 1hour pre RD is required.