I don't work there, but it's common knowledge that the upgrade time is pretty long. I think seven years right now. There are a lot of career pilots towards the top since it's probably one of the best regionals for labor relations, and they've been on a hiring spree the last year or so, so there will be many ahead of you.
Complicating this are whispers of ExpressJet integration; that's speculative and may never happen. But if it does, it'll be interesting to see how seniority lists are integrated (and how many more people are suddenly ahead of you).
SkyWest is a good company, but if you go, just realize you may be in that right seat a long time.