Do Now: You know the bus schedule, informally if at all. You also know that your up or downtown train runs about every few minutes in the morning. You know all of this because it has become second nature to you. Therefore, you can try one of two things tomorrow morning. One, you wake up early, see exactly where and when the crosstown bus comes, then time exactly how long it takes to get to the subway station. After treading down to the train (carefully, of course), time the trip to your school. Door to door time varies slightly based upon the situation and the day, but not by that much. And even though you arrived early, you’ll have the peace of mind of knowing the approximate length of your commute should you ever want another few minutes of sleep.
Two, you guesstimate the time it takes to get to work. Nevermind that you’re basically hung-over with exhaustion every morning while you sleepwalk to work; you’re an expert, and your instinct is better than any sort of empirical data you might collect. Wing it. Wake up when you do and ballpark your commute. Just don’t get too angry when your train is crowded because you mistimed the last one and now you’re dealing with ass-hole commuters who take up two seats. And also don’t get too wound-up by your students, also caught on the late train, singing the latest top-20 hits to the beat of their i-phone speakers. Oh, and also ignore the fact that some trains are limited during commuting hours (like the uptown 6 train to Parkchester). That’ll add only another 5-10 minutes to your commute time. But since you didn’t budget that into your estimation, it looks like you might be late. You might have to call your department and look like an ass-hole while they scrounge up both sub-work and an excuse while you sit at Parkchester and look like…well, an ass-hole late to work without an excuse. But at least you’re an ass-hole that means well, mislead only by the innate instincts we all possess.