It is hard to answer your question without knowing exactly what the order states. Generally, the court orders interest at the legal rate of 10% per annum (year) from the date that the installment payment was due. I have seen orders that provide a grace period, and if not paid within the grace period, then the 10% starts accruing. Again, it depends on the specific language of your order.
This is a general response to your question based on the facts provided. This response is for information only and does not constitute legal advice. This communication does not constitute, nor does it create, an attorney-client relationship