It does no good to get all over laffter here. Simple education it what he needs. To him, and any other newbies here: First of all, if a sup says something funky, like working before your start time, even if it makes your work day easier, stop and ask yourself, who really benefits from this? laffter's situation, obviously, benefits the preload and the sups more than anyone else. So what if it makes your day easier? you guys/gals are here to make money, not work as easy as possible. Too much bulk? That's a management issue. Think this through...Too much bulk, more time and money for you.
Second: always keep track of your time, whether you are a driver or a part-timer. Mistakes WILL be made. Most of the time they aren't even intentional, but does that really matter? If you don't keep track of your time, you would never know you were shorted. So always keep track of your hours.
Third: do not be surprised but your sup's actions. If you work here long enough, you will find this isn't an isolated incident. Maybe it's pressure, maybe it's just a stain on humanity, but don't be surprised when it happens, because it will.
Also--check with anonymous for sure--it used to be that if you started before your posted start time, that time before the posted time was overtime. Not sure if that is still true, but it's worth checking.