As far as I can remember, we have only 2 examples of R'hllorrections -- Cat and Beric. Both of them deteriorated from their former selves after resurrection, Cat moreso probably because she was dead for so long. Based only on that we can infer that Jon will be weakened in some sense, mentally or physically. iirc Beric was a powerful fighter beforehand and we've only seen him fight once since then where he lost to the Hound. Losing to the Hound doesn't really give us any evidence that he's deteriorated physically, anyone could lose to Sandor because he's a beast. He held his own pretty well too, but was also using fire which gives him an extra d20 roll per turn. Mentally both of them lost something, Cat seems to have lost her humanity entirely, and Beric lost memories and a general feeling of self, but even that is tough to narrow down because he was resurrected so many times. All things being the same, Jon should at least a small degree of his old self mentally.

The main difference between Jon and those two, however, is that we know he's a warg. Fully sharing a body with Ghost may or may not have an effect on his resurrected mind. If we assume it WILL have an effect then he may come out a little more feral -- which usually means he'll be more emotional and aggressive. Or Ghost will serve as a nice furry incubator, and he'll come back just fine except for the newly added scars and chip on his shoulder. Either way I can't imagine that Jon comes back anything but super pissed off and ready to kick some ass. (If he loses some memory though, I wonder if that could trick him into seeing Farya and not recognizing the change.)

As far as WHEN it happens? In the book it can't be too early, the Battle of Ice will have to be written first, and I imagine that'll go hand in hand with the siege or Mereen. So 1/3 through the book at least. This late in the series does seems like a prime time to expose the secrets of Redurrection, and since Mel has never done it before-- wouldn't it be fun for us to experience it for the first time along with her? There has to be a significant amount of plot stuff for Jon to move from the Wall to Winterfell (assuming that's where he's headed), so it's very possible that we get a Melisandurrection very early in the book, and Jon's plot takes as much time to develop him getting to Winterfell as it takes for the Battle of Ice to play out in page-time.