The starting point of the vehicles very much depends on the AFCAD of the particular airport in question. If they have vehicle parking and vehicle paths set, they would start a lot closer to your aircraft. That said, I don't know if the FSLabs calls for each action one at a time, but normally when I fly the Boeing 747-400, I'll call for boarding when refueling is getting close to being finished, and usually the baggage carts show up as fueling is going. Of course, I have it set, so the refueling takes place from the left side, so that may have something to do with it.