Land transfer taxes are paid on new construction condos (and resale houses/condos for that matter) when you transfer title and ownership from one party to another.
For new construction properties, there is the point you move in and occupy a property (called interim occupancy) and then there is the point that ownership is transferred into your name and you get a mortgage (which we refer to as registration).
You pay Land Transfer taxes at the latter point (on registration), when you get your mortgage, NOT when you generally move in and occupy the space (interim occupancy).
As always, consult with your team of advisors when buying to understand the specifics of your situation.