It varies by BES. Check your latest composite report and see where someone close to you falls in the x/x Reserve portion. That will tell you where you might fall seniority-wise in Reserve. Check the number of reserves versus the total pilots in category. It's not as simple as straight-up seniority. I understand it's complicated as I've spent months figuring out myself, especially when considering a change in equipment via AE's.

I've probably already said too much. REG good RES bad.