A: According to John’s original rules, and the ones published in PwP, it’s at the end of your turn. Either through confusion or Andy’s tampering, it changed to any point during your turn, as of how they are in the 3HOUSE booklet and in the newly reformatted PDF and webpage versions.

Except note: SuperDuperGames implements it by the “old” rules, while Looney Labs’ Pyramid Arcade lists the current rules which say you can do this any time during your turn.