Your tree will be well watered upon completion, so we suggest letting it drink and absorb it's first watering at least a week before starting the watering process. Which includes the bucket challenge... If you choose to accept the challenge, we suggest 2, 5gallon buckets a week for the first 2 to 3 weeks. And depending on the heat level, it is better to let your tree dry out than over watering it. Trees are capable of drowning and developing root rot.
As part of your design, mulching your tree will help keep moisture in the soil. It is still ok to use rock as part of the ground cover, but it may require a little more attention.
With the hot summers in Colorado we often experience, the sun will heat up those rocks and act as an oven basically, drying out the soil much faster and needing more attention to watering. I have found that using a hydro meter can be helpful in gauging whether or not to add more water to your trees or shrubs. It is not a good idea in my opinion to rely on sprinklers to properly water your tree or shrubs in the first few months of its new home. Not completely getting through to the roots in need.
The first year of your tree's life will be developing its root system. So don't be discouraged if you don't notice a major difference in growth until the next season. However the watering schedule for the second year is generally a lot less and can maintain it's moisture naturally that mother nature provides. Just remember that mother nature also provides extreme temps in the mid-summer months and still may need more attention to not completely dry out.