CWM030
If you look here you should be able to see how many days you have until your data resets. Your monthly data reset will be on the same date every month. If it started/reset on the 13th, it will reset on the 13th of each month.
Edit: I should add that, because it's the same date each month, some data months will be 30 days and others 31, and even 28 or 29 when it concerns Feb 13th thru Mar 13th. Also, though the system will warn you if you get to a point where you've used more data than you should have at a particular time in the month, it never hurts to know how much you should try to stick to each day. Like with mine, I have the 20GB plan, and with my data reset being on the 5th I know that I need to stick to around 667MB or less per day in this current cycle.
Lastly, if you primarily use Windows and/or Android based devices, Glasswire is a great tool for telling how much data a particular device is using, and just what on that device is using it, as in programs and apps. It's a free program, and it can come in really handy, especially if you seem to be using a lot of data, but don't know why. It monitors the data used ONLY for the device it's installed on, so it would need to be installed on each device you would want to monitor the data usage for. With a limited data internet service like HughesNet, it can be important to know just what's using your data. 🙂