@theoptimist, it was nice to see someone being worried about phone than other things before landing here, lol. yeah you can have the phone the very same day you land here. Couple of things for people landing (specially students) to keep in mind;
1. from day one, you can visit a bank (Scotia, RBC, Montreal) these banks offer student credit card with no income proof or deposit. The limit offered is 500CAD which is good to start your credit credibility in Canada (doesn't matter how good or screwed up your credit score was in your respective country).
2. As you are new here and don't have any credit history, buying iphone5 could be a little tough ( what I meant is with no deposit case). you can have a phone worth 300 to 500 CAD without any deposit by just using your Credit card (they don't charge you on your card, it just to show them) and you can have a plan with them.
3. phone plans, as compared to UK or India, it's expensive here.
4. If you are bringing your own phone, better check the frequencies Canadian carriers run on.
5. once you buy a phone with contract (which is called TAB instead of contract) usually for two years or three years, you got keep that plan or else whenever you quit the plan, you got to pay the value of the phone (they have the valuation sheet with them).
6. Once the contract is over, you can get it unlocked and use it with any carrier or upgrade your hardware with the same carrier at almost no cost.
Cheers!