I started billing at the end of the month. However, I got tired of having to bill on the 31st, then checks didnt get to my PO BOX for 1-2 weeks. Once I learned my route and accounts better I would send bills out halfway thru the month. The bills would already have all the cuts included on them, This was because I knew the accounts, and I knew which ones would always get cut. Now the client has the bill 1-2 weeks early. Some might wait until the last service is performed, and then send payment, but I noticed 80% just pay it when they get it. That definetly helps my cash flow, because its ALMOST like getting paid in advance. However, I do have a few select accounts that pay me upon each service. They were slow payers or non payers in the past. So I still service them, but must be paid before the trailer gate goes down. This is only because I have other clients on the same street, otherwise I wouldnt touch them. Hope I helped.