Can:

Being late on the first payment is a bad sign. This is not shame. Shame would have paid it. This is selfishness. You need to set a firm boundary for him. She is very young and you have a long way to go. You can't feel guilty about asking him to support his daughter, particularly when I assume you have a court order in the divorce. Send the bank account number and routing number and let him know it was due on the first and you need him to make the payment immediately and timely make the December payment. If it persists into January, don't mess around, I'm sure your state has a child support registry he can be made to pay into so they can be the bad guy instead of you for enforcement. They may assess a small fee, but it will be well worth it for you not to have to deal with it, particularly if it gives you anxiety to even ask when he is already 3 week late.