Hi, I'm very new to doing commercial, been mainly doing domestic window cleaning, I am starting cleaning for a large shop and they want it done weekly. So I was going to invoice them at the end of each month. Not sure how long to say I need payment within on the invoice/agreement, like 14 days/28 days?? I've been doing this now about 2 years and never done a job weekly. If I say 28 days and they use the whole of that period I'll be working in arrears. Whats a good time frame to request payment for commercial? Thanks.