once a day usually on working days.evening time when updating days work,inputting new customers,changing details,adding work notes,adjusting round order,printing invoices,texting customers,phoning potential new customers etc,etc.
i run a tight ship so i keep an eye on non payment.text reminder after 14 days usually does the trick.
i prefer cash or cheque on the door to be honest.luckily i have some big chunks of compact work that i collect from.good cashflow and i like to see my customers and ask how they are!