Dan and Victor___(出发）early so that they could arrive there on time.

Dan and Victor set off early so that they could arrive there on time.

Dan and Victor_left__(出发）early so that they could arrive there on time

Dan and Victor【set】【off】early so that they could arrive there on time.
Dan and Victor【set】【out】early so that they could arrive there on time.
Dan and Victor【started】【off】early so that they could arrive there on time.
Dan and Victor【depart】early so that they could arrive there on time.
Dan and Victor【left】early so that they could arrive there on time.

Dan and Victor___(出发）early so that they could arrive there on time.
departed