Totally Tardy Marty by Erica S. Perl
Totally Tardy Marty just can't seem to get to school on time. Not when there are so many better things to do in the mornings, like invent Toast on a Rope, fight a giant squid in the laundry, or follow some ants up a tree. And so he's tardy, every day, much to the smug delight of Never Late Kate, who thinks she's sooo great. But then one day, Kate helps Marty out of a jam (or rather, a tree), and the two end up playing together, have a surprisingly good time, and are both late. The two strike up an unlikely friendship and learn it isn't the worst thing in the world to be sometimes late. Together, Marty learns a trick or two for punctuality, and Kate stops to smell a rose now and then, or inspect an anthill.