Right.The question is not how will Scotty be introduced, but how will McCoy be introduced, he's not supposed to be there.
How do you figure? Just because McCoy wasn't seen in either pilot doesn't mean that he wasn't involved with Starfleet. You could easily say the same about Chekov, who wasn't seen until Season Two.
There's good reason to believe that McCoy wasn't serving on the Enterprise when Kirk first took command. But there's also good reason to believe that Kirk and McCoy knew each other long before that point.
The sad thing about most of these conversations is that everyone seems to assume that all of the pieces have to have fallen into place simultaneously. Suddenly, out of nowhere, these people suddenly appear, all at once and all as we remember them.
We know McCoy knew about Carol Marcus. We know that Kirk knew about McCoy's "one woman in his past" and so forth. The first time we see McCoy, it's clear that they've known each other for a while. We know that McCoy has been in private practice at least once. We know the McCoy did other things before serving on the Enterprise.
All that is very logical. These people, were they "real" people, would have had LIVES that didn't involve only these seven other characters.