There started to be more talk after the Revolution tour. I would imagine any thing earlier would have been at 1st Ave unannounced shows.

I could be totally wrong. And if I'm wrong, I would like to hear those shows.

bigbrother said:

I'm not asking for any bootlegs but just curious to know what was Prince's first after show?

It was at Busby's in London on 13th August 1986, he did one the following night at Kensington Roof Gardens, also in London.

Check Prince Tour History. https://sites.google.com/...s/One-offs

Now, those earlier one-off performances could have been select dates, a showcase, or a random club appearance. As far as after-shows, you'd have to bounce against the tour history itself, and line up some dates. But, it's a good place to find dates, at lease.