Stopped using my computer on the 19th because I received a message that I was at 90% of the usage. Skipped using the internet for the 20th. Started again on the 21st because Verizon's email notice said "Your monthly data allowance will reset on the 21st." They do not say it resets at the end of the day.
I thought it was at the beginning. Called customer support to ask if they could waive the overage fee this one time. The rep didn't seem to understand the difference between resetting the usage at the beginning of the day or resetting the usage at the end of the day. She just tried to justify Verizon's method of communications saying it was clearly stated that the usage was at its limit.
Take some time and read the wording in Verizon's notices. It wasn't clear to me, obviously.
First time I had a bad experience with a Verizon rep. In fact, I was waiting for a feedback form from Verizon and nothing appeared in my In Box so ended up posting this note to everyone rather than just Verizon staff.