Things that will make a difference

1) seasonality - more lines summer than winter
2) hire rate - Even in a busy hiring year, there might be 3 months where 800 pilot get hired and 3 months with 100. That could make several months difference getting a line
3) base - big coastal bases quicker than interior hubs quicker than the 737 only outstations
4) senior people bidding reserve (which does happen now)

If everything comes together you could have a line your first month off IOE. Tip a few options against you and it might be a year. This doesn't consider bases where it currently takes significant seniority to even be the plug (eg MCO)