You need to have your court order amended, because if you are ordered to pay it on the 1st and if you pay it only by the 15th, it is by then two weeks late. If you are living paycheque to paycheque- as most people are nowadays- then you should make your case to the judge and ask that a portion of each of your pay cheques be taken so your support is paid. It might be best if you have it garnished automatically so that you are not even tempted to break into that money. I pay support and that is what I do, because my budget is tight and previously I kept having a problem with it. Certainly don't wait until your ex complains to your local enforcement agency or files a motion against you in the family court herself, I suggest you be proactive and do this yourself so that you have a bit more control of the outcome. Good parents pay support! And don't forget to take out a life insurance policy in case anything should happen to you, your children still have needs until they have graduated from college or university. Good luck.
Have both paid and received child support and have been to court about it so know the ropes somewhat.