First stage for an Inland applicant (AIP, or Approval in Principle) is currently ~ 17 months.
Since you have been here without status for a few years, I'd suggest NOT leaving (if you apply Inland), because CBSA will likely refuse you re-entry because of your overstay.
Inland applicants are always at risk of having their application cancelled if they are refused re-entry into Canada. While most people that are visa-exempt may not have any issues, it's never a guarantee...even with proof of a spousal sponsorship application. In fact, IMHO, it may make it worse, since it's highly unlikely that the person has any real ties back to their home country...because they are [semantics aside] living in Canada now.
CBSA wants to know that while a person is seeking re-entry into Canada to `visit', while they wait for PR, they also have a `home' back home (and a job, bank account, etc.).