Ask What is a reasonable amount of time to give a client before following up on an unpaid invoice?

[Edward22]

Getting paid on time is very important, but I feel it can be uncomfortable to ask a client about money too quickly. At the same time, waiting too long can cause problems, especially if bills are involved. After sending an invoice, how long should you wait before sending a reminder without seeming pushy? Also, what kind of message sounds polite but still serious enough to show that you expect your payment soon?