My own experience is that once an application is in the mail room,
it takes 2-3 days until the check is cashed and 7-10 additional
days for the receipt to arrive.
However, you need to know the delivery delays. I once sent them
a certified mail and it took 8 days for USPS to get it to
Laguna Niguel.
So track your package and find the date of arrival. If more than
a week or two passed from this date and the check was not cashed, you should panic somewhat (Although I have no idea
what to do at this point).
HTH,
HR04