I'm Doing Okay

Every once in a while, I get random emails from Verizon that tell me how I'm doing with regard to my monthly data limit:

My initial reaction is slight annoyance, because why do I need an email if I'm doing okay on data? But ok, at least they're trying to give me some information so I'll accept it. Even though (oddly) they sent it at 4:20am.

However, there's a terrible problem with this email. See if you can figure it out before reading on.

The email doesn't say what day the month ends! The email is dated March 4th. If the month ends on March 31, then I most certainly am not doing okay on data. So when does my data reset for the next month? I honestly have no idea.