The company I worked for would send a past due bill (it was really just the next months bill with the past due amount added to the new monthly charges) and then 20 days after that statement date the services would be reduced to minimum service. That came out to be a total of 50-51 days (depending on a 30 or 31 day month). Then, after another 10 days if the bill wasn’t paid (at least the past due), the services would be stopped completely and a final bill would be sent out.
One company I have services with don’t shut them off until you’re 3 bills late, but when they get shut off they’re shut off completely and require a reconnect fee and full payment.
Either way, if you’re having trouble paying, the best thing to do would be to call them and explain your situation and discuss payment options.