I have had issues with a large airport where turnaround vehicles take a long time to get to a stand, causing delays in departure. So, I suggest that turnaround vehicles go to a stand preemptively and await the aircraft’s arrival, like how in real life as soon as the plane gets to the parking spot, the baggage trucks, people, etc are already there ready to start.
It is already like that. If you look closely when airplane leaved runway, ground vehicles start to roll out and go to stand.
However if the distance in between depot and stand is too much, it may cause delays. Then I suggest you to park vehicles to stand’s itself or another depot close to stand.