Ask HN: How long did you wait before your employer sponsored your Green Card?

I'm considering a move to the US from Canada but if I move down I want to follow a more permanent solution to the visa situation rather than working on a TN (NAFTA) visa.

I work for an international bank and so transfers to a US office should be possible under an L1 visa but I was wondering, typically, how long does an employer wait to start the process of getting a Green Card under EB2?

From first entry to citizenship the timeline in the US appears to be min 8-9 years which is on the longer side globally (Canada gave me citizenship in 4 years).