One of the most stressful things that children have to deal with during their parents' divorce is having to move back and forth between homes. For likely their entire lives, they have been living in the same house with both parents. The days that might be the hardest for them are the ones when they go from one parent's house to the other's. It is up to both adults to help them thrive despite these challenges.
Children who understand the concepts of days and hours might benefit from knowing the schedule ahead of time. This could help them plan for the transition ahead of time. You might consider making a calendar to show when they will go to the other parent's house. If there are schedule changes that deviate from what the child is accustomed to, let them know ahead of time.
Another important way that you can help them is to have a dedicated space for the child's things at your home. This can be a room or a dresser. Make sure that they have clothing and other belongings at both homes. Some children get stressed out when they have to pack bags to go back and forth. They might feel like they don't truly have a home. Of course, there might be some items that do need to go back and forth, but they should still have some items that remain at each home.
On the transition days, try to keep things low-key. Don't discuss any contentious matters with your ex during the transition. Let these days be focused on your children so that they can go from one home to the other without arguments or tension. You might even consider having terms related to the exchange added to the parenting plan.