Instantly. Have you checked your spam folder just in case? Did you order with Paypal that might have a different e-mail address attached to it than the one on your Impulse account?

If none of those are the case, chances are your order got flagged for manual checking for fraud prevention. Stardock (and all digital retailers, really) always have to deal with credit card fraud, and they get penalized pretty badly if they let one through, so Stardock's fraud checks are a little stringent. The queue is processed manually, but I think a day should have been enough time.

To be sure, you should send an email to sales@stardock.com and check up on it.