I think now they give you the range of dates and we just come during the given dates. That's what Ive been reading so far.The landing letter will come directly from Montreal office giving you a time and date for your landing appointment and giving you details of what to bring for the interview. I was away from the forum for a while, so things might have slightly changed, but this how it used to be.
I'm waiting for the last one letter interview thing too. The immigration told me the longest wait would be up to 8 weeks for Montreal office.