in most cases, purchaser will have a lawyer. and seller will also have a lawyer. purchaser transfer the funds into laywer's trust account a few days before the completion date. at the completion date, purchaser's lawyer will check the legal title at the last minutes and then register you title on the property. once they did that, they will release the funds from trust account to the seller's lawyer's trust account. seller's lawyer will disperse the funds to the seller after expenses.
the PTT is remitted out of the purchaser's trust account unless you are 100% exempt. in the case of exemption, you lawyer will fill out all the forms and submit them to the local land registry office when he register your title on completion date. if you are not 100% exempt, he will have to remit the funds to land registry office when register your title.
HST is completed because the changes of legislation. it was GST only before july 1. i am not 100% sure about now. but it used to play like this: developer charge you GST on the purchaser price, the amount you paid to developer including GST, afte the completion date, your lawyer would submit a GST rebate application form to federal tax department, once you GST rebate applicaiton form is accepted by federal tax department, your lawyer's trust account will be credited for the amount of rebate, in other words, the whole process will take a while.
i can only think of one situation that developer credited HST directly to you: you paid 100% cash to the developer, and you and your developer hired the same lawyer.
BTW, talk to your bank for lawyer referral if you need a mortgage. bank normally give you a credit for lawyer's fee if you hire the lawyer recommended by the bank.