OK, a little more ...
The producers of the grafted Neal Peterson trees is Forrest Keeling. Link:
https://www.fknursery.com/page/Forre...terson-Pawpaws
Of those 6 varieties I grow and know 2 very well, the Shenandoah and Susquehanna. Shen is probably the easiest to like for 1st time tasters - mild taste, and also seems to come into fruit quicker. Sus is my favorite of the 2, has a stronger flavor and texture, and more meat. Potomac I have tried from others, and it is a winner - good flavor and honking fruit size. I am sure the others are good also, I just haven't gotten to them yet.
Now as to timing with grafted trees. This is up in Iowa, and they love our climate and deep good soil. These have the good life, with about 4 inches of compost on the surface.
Shen planted 24" grafted tree. After 2nd summer it was 56" and had its first flower buds. No notes on the next few summers - and it was not near pollen source so may not have fruited. Next notes are after the 5th summer (by then other varieties probably caught up and bloomed). It was full of fruit and up to 2nd story window.
Sus grafted had flower buds after 4th year.
Now lets go to notes on seedlings. Not to be grim, but out of 76 seedlings only one was up to the quality of Peterson trees and other excellent varieties. I don't have the source of the seeds other than "improved seedlings", which I think means out of an orchard of at least semi-good trees. Of the rest, about a half dozen were candidates for a few years, which meant they were scoring pretty high on the basics like size and taste. Some were kicked out on relatively minor things like a little starchy aftertaste, or susceptibility to a disease that causes black spots and skin cracking (and this could just be from other factors like position in the orchard). Timing - most of these took quite a few more years to bear first fruit, and a few still haven't after about 20 years. Given these low odds I still plant seedings just because they are easy and cheap, and you can always graft to them if too bad. Now I have the luxury of better seed sources (like 2 excellent varieties planted together and remote from other pollen) but do not have any results on these yet. But at home where I have limited space I go for the good grafted trees and love 'em. Good luck with your pawpaw patch.