|Porter isn't unionized, but it does respect a seniority list.
Looking at the Oct 01 2016 Seniority List, the most junior Captain flying the line was hired in Oct 2013.
There have been Upgrades classes in progress in the last few months; with the next one slated for early Nov 2016.
In the Nov class the most senior FO was hired in Nov 2007, and the most junior Apr 2015.
Overall, however, if you look at the 30 most junior captains, the average is 30 months (2.5 years) as mentioned before.
The most senior being Jan 2013, and the most junior May 2015; the bulk (middle 20) being hired in the first half of 2014.
As for hiring experience, they would prefer:
Direct Entry Captain: ATPL, 5,000 hours total time with 500 hours PIC on type or 1,500 PIC Heavy Turboprop (in excess of 44,000lbs MGTOW). Entry Level First Officer: ATPL, 3,000 hours total time with 500 hours multi-engine PIC.
As for upgrading, the VP Flt Ops, DFO, and CP look at the candidates seniority, experience/qualifications, and employment record (PPC/rides).
There is matrix when it comes to qualifications:
Option A: Minimum 2,000 hours PIC, and 500 hours on type (Dash-8)
Option B: 3,500 hours Total Time, and Minimum 750 hours PIC OR Minimum 500 hours Multi Engine Turbine PIC, and 500 hours on type (Dash-8)