My terms are net 30 but I really don't get too worried until the 45th day. I invoice individually as opposed to sending a monthly statement. So when I receive a check for several orders the average is usually around 30 days. 

Many years ago I owned a manufacturing firm and we invoiced at 2% 10 net 30. Many of my wholesale customers would honestly take the 2% and pay within 10 days but many just defaulted to the 2% regardless of when they paid. It was a bookeeping nightmare trying to keep straight who had taken an unearned discount. I really don't want to relive the experience.

We also had a penalty for payments over 60 days but this proved almost impossible to collect unless we filed suit on upaid invoices. Since we had included this penalty on the invoice it was enforceable in the suits.

So much for my input from previous businesses. Today I am satisfied with payment within 30-45 days although I really respect and appreciate our clients  that pay twice a month.