The answer is NOW! You don’t wait until 1 December 2023.
That’s if you are entering into any kind of an agreement with anybody. If you have no one at all, then, don’t worry, you don’t have to explain anything to anybody.
However, if you are entering into a Listing Agreement or Buyer Representation Agreement today, that runs over 1 December, you better EXPLAIN the TRESA issues NOW. Like, for example, the fact that you will be disclosing their secrets on the selling side etc. They might be upset and not want to hire you.
Have a look at s.22.2 of Reg. 567/05 as amended by Reg. 357/22, s. 12.
“22.2 (1) If a seller has a legal obligation to disclose a fact to the buyer and the fact is known to the broker or salesperson who represents the seller, the broker or salesperson shall disclose the fact to every buyer who expresses an interest in the real estate.”
Brian Madigan LL.B., Broker