Can a coupon be set for discount on first month only of membership?

I've got the membership plugin installed on http://miraclesformommy.com, and client just emailed asking about coupon codes. It's a first time for both of us working with this plugin, so I took a look at the coupon area, and it's not immediately clear...

Client wants to add a coupon code that's only good for the first month of the membership. Is that possible? Or does it have to keep cycling each month when the subscriber is charged?