Good points & clarifications. OK, so one of the "facts" that I always thought was true about this case may not have actually been verified.
I.e., at the least it seems like both the neighbor & JJ's brother actually saw him pulling the garbage cans up to the house - while in the driveway. However, it may not be 100% verified that either one actually saw him walking down the street. So, if this is the case - then there is no way to confirm which direction he was walking towards when he left the house.
I also agree that we don't know the exact time(s) that everything happened that morning.
By all accounts, it appears that it would take JJ roughly 15-20 minutes to walk to the H.S. parking lot from his house - without taking any side-trips along the way. Also by all accounts, the weather was clear that morning - so it shouldn't have taken him longer than usual to get the H.S. (as it possibly would have if there had been excessive rain/thunderstorms that morning, etc.)