Is it too late to set up Refer a Friend? (WORLD OF WARCRAFT)?

I've recently decided to start playing WoW because all my friends have been saying how great of a game it is.

They told me if I ever decided to start playing, that I should let them know and they'd Recruit me on battle.net.

Here is what I've done so far:

Created a Battle.net Account

Entered the code for the World of Warcraft Standard disc I purchased

Set up payment for $15 monthly through PayPal.

Is it too late for them to set up Refer a Friend?

Is there a way I could redo this without having to pay $20 for World of Warcraft again?

PLEASE HELP!