The trees probably don't need rooting hormone to get going, becasue they already have roots. If you want to add the root starter it does seem to help newly planted trees in establishing a good strong root system and minimizes transplant shock.
However, the most critical thing the trees will need to survive and thrive after planting is water. Be sure you water the new seedlings in well after planting and then keep watering them well through the summer months. We suggest you continue to water them in the winter months as the weather dictates. Then in future years you will want to keep up with the water needs of the growing plants and water as needed.
If you need more specific information, please as when you pick up your trees Friday night.