I'd guess you'd get it during your first year, assuming you were able to get a 737 slot during your class drop. While the 73N does "go junior" all the way to new hire classes, not all new hire classes offer it. It just depends on the exact class you're in. You may have the class before and after yours get it while yours doesn't or vice versa. If you don't get it, then I'd guess exactly one year.

As for getting off reserve, that's a harder guess but I'd lean towards thinking of it in terms of years. Even if you hear a story of someone getting a line almost right away, that could be a one off. I'd think 1-3 years on average, but obviously it could change a lot either way. Its a small base with not much room to grow and senior over all, despite the junior portion of it going to newer pilots.

YMMV.