I agree with above postings. No pay, no stay.
Take payment in advance of care, ie all on the 1st of month or divided between the 1st&15th
Or on the Friday of the week before.
I do post dated cheques and take 6 months at a time so I have the payment. I’ve only had an NSF twice in 10 years
Make sure it’s all in a contract, as well as late payment fees per day of outstanding money.
If you don’t have the payment, refuse care to the child.
Make sure contract says you will take them to small claims court for non payment and they must reimburse your costs for time of work related to appearing in court.
Be clear on your termination clause- ie how many instances you do/don’t allow for late or non payment, and then follow through. Every time you tolerate that behaviour, you have weakened your own credibility, and they know they can continue to do it again.
Stand up for yourself and your business.