I called the Sprint NWA operator two days ago, to ask the same question. I was told my the Sprint operator that my 5,000 mile bonus had been sent to NWA, March 15 (signed up Feb 2)

The Sprint operator furthur explained that after NWA recieves the miles notification from Sprint, then NWA is responsible for posting the miles to each account; which the operator said usually takes 6-8 weeks to show in your account...