Hiya,
I am in Ontario on a TWP for three years. I shipped about 6 boxes of assorted things from home.
I didn't fill in any paperwork prior to leaving in this regard, and when I arrived at the US/Canada border (I drove into Ontario) I told them that I was shipping some things from home.
I can't recall if they had me fill in a form then and there, but I'm pretty certain that they didn't - and as my belongings are deemed to be temporary imports, they weren't taxed.
When they arrived about 6 months later, the shipping agent forwarded the customs form to me, which I then had to take to the airport to declare. I confirmed that I was here temporarily, and the understanding is that my things will be leaving with me when I go home (though most will end up trashed before then, eg clothes). I had my form stamped, no tax or fee was required, and then the shipping company was able to deliver my goods.
So long story short - as a temporary worker, you shouldn't have to pay tax on your items. When you arrive in Montreal, just tell them you've sent some items - you'll probably need to show your shipping consignment - and they'll either have you fill a form there, or have you wait til everything arrives, like they did for me.
Hopefully that hasn't confused you!