You should still get credit for recruiting them so long as you do it within 7 days of the player making an account OR they have been lapsed on their account for over 24 months.
Here’s the support article on the program for you- https://us.battle.net/support/en/article/46861
To recruit a friend, your friend’s WoW account must match one of the below descriptions:
- Your friend’s account is new, created in the last 7 days.
- Your friend hasn’t paid for game time for over 24 months. If your friend has returned and paid for game time in the last 7 days, they are still eligible to accept your invite.