BOWP (bridging open work permit) — when am I actually eligible to apply for one?

Broadly: you need to have applied for permanent residence under an eligible in-Canada class (CEC and some others) and hold, or have recently held, valid temporary status, and you generally apply for the BOWP close to when your current permit is expiring, not the moment you submit your EE profile. Timing the application window right is the part people get wrong — read /guides/work/bowp for the sequence, and if your PGWP is close to expiring with no PR decision yet, don't leave the BOWP application until the last week. General information from my own experience, not legal advice — for anything specific to your file, a licensed RCIC or immigration lawyer can look at your actual documents.