The answer depends on whether you already have a separation agreement or court order that requires him/her to pay child support. If you do, you can register with the Family Maintenance Enforcement Program (FMEP) and they will monitor and enforce payments. There does not have to be a history of late or missed payments in order to register. The FMEP can also help collect the arrears that are outstanding at the time of registration. Sometimes the wording of your agreement or order is insufficient for the FMEP to enforce the terms and you will need to take extra steps to obtain a revised order or agreement with adequate terminology. You should consult a lawyer for legal advice if you have questions about the wording.
If you do not have a child support order or agreement then the FMEP will not be able to help you. I recommend that you speak with a lawyer to discuss your entitlement to child support, the possibility of your ex paying retroactive support, and the process of obtaining a court order or agreement.