Honestly keep it simple, unless you don't mind extra waits, possible delays and even being stranded for the time being at a station. If you take a school bus, you're likely to only take one form of transport back and forth and will require less time to stop over, wait, etc. Honestly, we should all be used to morning times, I don't see a problem with 7:20 am for you, and chances are you might forget something valuable e.g. a ticket on one of the couple train and bus rides compared to the one bus journey. You would also be very familiar with the exact route. Let's not forget there are a lot of irl workplace issues, strikes, and walkouts. Do not be tangled up midway through your journey basically, you would rather be stopped at the start or the end of the line, if that made sense.
Hope it helps decide. It really depends if you are the early morning type of guy, who is also careful with tickets and fares and is looking for more independence on regular methods of public transport. I myself will stick to the one bus ride.