Bought wow for a friend, how doesn he redeem it?

I recently got my friend who has WoW starter edition the Heroic edition for Shadowlands. On his blizzard account it says that he has no gifts pending and whenever he goes into the game it still shows that he is on a starter account. Is there a time limit on how long its supposed to take to hit his account? I figured it should be there immediately or if not it should show up in his gifts on his account.