The same as what I have done with all my dogs. Which now that I am trying to think about it I am not really sure what I do....
But I dont swap it for somethingk better/treat them, and I dont tell them off either.
I just "expect" them to hand it over...and so they do.
I owuld imagine a smart dog would soon learn than in order to get a good treat, it could just go an dpick up a shoe....or whatever. Why start them off with swapping the toy for something and then stopping th swap later, when you can just not swap in the first place?
Its just a personal thing I guess.