Check on Invoices Early and Often - at First
So on that crucial first invoice, I check right when it's due - sometimes asking the person I dealt with, but more frequently, now, going right to the accounts payable department. These people aren't shy about talking money and actually expect to hear from their vendors with problems and questions. Call and ask how the process works and see if they have your invoice. Explain that this is a regular process you go through to make sure things are working smoothly and to better understand their process, and that you're not standing over their shoulder about when you will be paid for this particular check. If there is a problem, like someone not filling out paperwork or an invoice not arriving from the buyer, then you can start taking corrective action rather than waiting weeks more and getting your stomach in a know. It's just business - so just take care of it.