Does the 3-day cooling period affect pre-sales?
No it does not, pre-sale contracts fall under a seven-day rescission period under section 21 of the Real Estate Development Marketing Act;
While I am at it, it also does not apply to leased land (such as First Nation leaseholds), residential real estate sold at auction; and residential real estate sold under a court order or supervision of a court.
Also, of course, it applies ONLY to subject free offers. If you already have subject clauses in the contract, they matter first.