"So I said, 'What seat should I take? Should I take the front seat or the back seat?' Realizin' that we were supposed to have a school bus. Guess what? We didn't have no money for a school bus (bus bus). But we made it work."
Well, that certainly puts things in a new light. In the original text of the song, she was meant to get on the school bus at the bus stop, which is where she saw her friends. Presumably, the second verse is actually set at 7:45
AM, which is why she wants time to fly and why she only mentions one friend at her side (most school buses only have two kids in each seat), and Fat Usher was passed by the school bus on the highway either in the morning (which would put it concurrent with the second verse, as the bus was cruisin' on the highway at that time) or in the afternoon -- not at night.
Everything makes sense now.