NSW home purchase: how long is the cooling-off period after exchange?

For most residential property purchases in NSW, the buyer has a 5-business-day cooling-off period after exchange, ending at 5pm on the fifth business day after the day of exchange. Auction purchases and contracts exchanged on the same day after an auction is passed in are generally excluded, and the period can be waived with a section 66W certificate. Official source: NSW Government. Guide: https://getinstantlaw.com/property-buying-selling/contract-problem