Hi Lee, As an adverb of degree, "almost" means something was on the verge of happening or nearly happened, but did not. So, to answer your question, you still made it to school on time albeit at the eleventh hour (the last moment). As a side comment, your need not use "too" with "late". You are describing whether you were punctual or not. We use "too late" to refer to something that should have occurred soon enough to make a difference. I would suggest: "I was almost late for school." I hope this helps.

It usually means "at the last possible moment"