I've got a customer that I mow about 4 properties for. He gets about 30 days to send the bill in before it is considered "late". So far about 5 weeks have gone by and no payment, ie about a week late. When should I start making phone calls? I dont want to harass the guy because he has payed before and gives me a lot of business. But at the same time I am not out to mow for free. What if he ends up not paying me.