Signed up for Blockbuster but it didn't "take" ?

I was signing up for Freeipods.com and at the Sign-Up screen selected Blockbuster. The Blockbuster page came up, i signed up, gave them my credit card but My Account on Freeipods.com is still saying I didnt sign-up for anything yet. And now when i go to the sign-up page of Freeipods.com and click on Blockbuster it says its no longer a valid offer. What the hell? Should I quickly cancel my Blockbuster membership-thingy and try another offer?

i think the blockbuster takes 2 weeks to get credit for it

oh bullshit! haha. I shoulda figured. So do i have to be a member for the full 2 weeks and try to cancel it before they charge me? Or can I cancel it after like 10 days?