He was still at the wedding when the kids were on the road to confront Logan. He had to take the call from Shiv, get Greg on board (that conversation was amazing), tell Logan what was coming and get there after Logan delivered the kill shot. The kids seemed to have been driving for a while too, as it was daylight when they first got the van and was already getting dim by time Tom and Shiv spoke.

At the end of the day, no matter how you explain it (or not) , that made for an awesome scene when Tom walked in