PSA is (and has been) upgrading 16 per month. If nothing changes, today's new hires are looking at about 1.5 years for upgrade.

If PSA increases the upgrade rate or if attrition in the F/O ranks rises, the upgrade time would likely fall to below 18 months. On the other hand, if they're unable to recruit new F/O's in a year and a half, upgrades will stall or slow significantly. Your mileage may vary.