All soil, sun and precipitation conditions vary from location to location, so is it impossible to have a black and white watering suggestion.
At the highest level the trees should be watered well at time of installation and the soil should be allowed to dry in between waterings.
Your new trees will tolerate a moisture rich soil more than many evergreens, but they will “drown” if kept overly wet.
Again, you should allow the soil to completely dry between waterings.
Generally, the idea for newly planted shrubs is to water more often at the very beginning and then decrease it gradually so that watering about every 7-10 days is usually enough. It is important that you take into consideration the location of your trees (i.e. trees planted in shady areas that have soil that holds water will need much less water than trees planted on a hill that are planted in soil that is less absorbent). Also consider watering less often if there is rain on a regular basis.