I'm with you... one to two years is lightening speed for the government! That said, it didn't take long for them to make the move from MMAR to MMPR, which involved a good deal of analysis, policy review, revision of rules, etc... clearly not the same scale as the next iteration, but that seemed to transpire between December 2012, and April 2014... a year and a half. (See Timeline)
To pass legislation on the subject and for Trudeau to be able to "keep his promise" 1-2 years is the only thing that makes sense. In the meantime I'm sure we will hear/see about drafts and rumors of what's in it. Remember, Trudeau needs to also pay for the tax cuts and programs he has proposed. I think a big sign of 'when' will start at the UN special meeting on drug enforcement.