Jolly Gerbils

• WWizards of the Coast2024-07-26
  Official Ruling
  The ability of Jolly Gerbils triggers when the gift is actually given. For permanent spells, that happens when the gift triggered ability resolves. For instants and sorceries, that happens when the spell resolves. It doesn’t matter if a replacement effect causes the gift you gave to become something else or if a static effect stops the player from receiving that gift.

Rulings via Scryfall