Back when I was tighter on cash flow I paid bills as close to the due date as practical. But now that I have more cash lying around I've been paying them whenever I think to check on my money. That is to say, if the statement is ready I go ahead and pay the bill, even if it's not due for another 2-3 weeks.

Clearly I could make a little more interest by waiting to pay the bill, but I think I've decided I'll keep paying whatever's been invoiced just so I don't end up paying something late because I wait another 2-4 weeks before checking on bills again.