Has finding out their diagnosis also led to you or their other parent to a late diagnosis?

I've gone the other way around.

Having gotten my ADHD diagnosis at 39, it's made me 90% certain that the struggles my kid had throughout school were as a result of undiagnosed ADHD. He's pretty sure that's the case too, but unfortunately he's now 19, so on the adult waiting list which may be a few years long at this point.

He's just finished the first year of a law degree though, so I guess he's managing to deal with it pretty well.

With regards to resources; a hearty second here for How To ADHD. It's a great channel, with some really helpful information.