August and Sept will still be just as hot as July, so if that's a major factor for you, then I would wait til late October or in to November when it starts to cool off a bit! Late Aug and Sept are, however, very low crowd times.
To OP i really think what you are doing is wonderful. and not waiting for someone else is the right thing to do.
Your post brought a tear to my eye. Even going later is fine. Anytime really as long as mom is remembered.
Yesterday Disney Visa finally released the dates for free DDP in Aug. and Sept. For now you have to have a DV to book but the dates will be opened up to the public on May 2nd.
The dates for free DDP and 8/28 to 9/24. So there's another reason to go in late August or Sept. We go in Sept almost every year and really love it then. Warm/hot enough to do the waterparks but not as crowded as summer season.
If you stay at POP it's free QSDP, 2 CS meals a day, no TS. So no worries about eating alone at a sit-down. We did QSDP for the first time last year and loved it! No ADRS! YEAH!
Sorry started reading when you first started wrighting ptr. Life got in the way so am catching up. The free dining plan is great. We are going in Sept staying at Pop and upgraded to the plan with 1table service. Hope you are still planing on taking trip.