For trees with larger root balls, you want to provide a deep watering. To do this, the hose needs to be left at the base of the tree while the water flowing at a steady (but not overwhelming) flow. Allow for 10-15mins for the water to soak down in the root ball. If you do this properly and allow it to be absorbed, you only need to water in up to 2 times a week. As with all plants there is not a specific watering schedule because there are many variables that come into play (rain, soil type, root ball size). You can always dig around at the root ball and see if it is dry too.
First 1-2weeks:up to 3 times a week dependent upon weather. Turn hose on mid to full, and water the base of the plant. Let the water keep sinking into the root ball for 15seconds. If too much water is running off, then the water is turned on too high. The goal is a deep watering. Do this every few days. The smaller ones probably don't need watered as much, but use your own judgment.
Important: Signs of over-watering can be yellow leaves appearing. Also, if the plants look like they are dying but you know you are watering them enough, then you may be watering them too much, too frequently. And signs of dehydrated plants are shriveled, wrinkled, curled up leaves. Look at them now while they are healthy so you know what normal leaves look like. Regarding rain: unless it was a steady rainfall for 4-5hours, then the plants need watered (maybe not as much) but still needs watering. Unfortunately a quick heavy rainfall will not sink into the root ball far enough, if at all because the mulch and leaves will also stop the water from reaching the root ball too, so keep that in mind.