A pH of 7 is acceptable. Don't try to change that. A good mulch is a help in most locations. If it includes some green material, compost, or manure your trees should grow fine. Too much fertility is counterproductive and can reduce fruit eating quality.

On most soils watering every 7-14 days is a good schedule.

Sorry, checked again: pH is around 8. These are test kits. I don't how accurate they are. Thanks for your help.

I would water newly planted trees more often than 14 days. If the weather is hot or dry, I would go for twice a week, especially if the soil is sandy. Northwoodswis

I'd say 8 is pushing it. On the other hand, inaccurate test kits abound. I wouldn't try and radically shift ph, especially now that the trees are in the ground. I started out a 7.5 and my soil is now 6.5 I added some iron sulfate at the beginning. Sold as "copperas" in my area. That helped. Also, most organic fertilizers and mulches tend to hold down PH. People on this forum I respect immensely say apricots are intolerant of sulfur based amendments, although I honestly did not notice. Anyway, they are more tolerant of alkaline soil, so you can avoid the Copperas for the Apricots.

I recommend organic fertilizers, not because I particularly subscribe to the method, but because they match the needs of the tree pretty well. The thing that works best for me are aspen leaves I collect on the property, put in a plastic garbage can and then shred with the weedeater. I also use cottonseed meal which I buy at feed store. Its supposedly acidifying, although I don't feel it gives me the nitrogen jolt I would like. Its also getting expensive.

Fruitnut is way more successful than me in raising trees, but I respectfully disagree about fertilization. For immature trees I would give them a couple of extra jolts of nitrogen fertilizer in the beginning and middle of the season until they got to a reasonable size. Although I agree with Fruitnut that overfertilization will hurt fruit quality, It will be a few years before they begin to bear fruit. You can cut back before then.

As you live in a high alkaline situation, you probably live in an arid climate. Therefore more frequent watering may be required. On the otherhand, I killed a couple of cherry trees with overwatering, which is real easy, especially if you have a thick mulch. I highly recommend one of those little moisture meters they sell at the nursery, especially for the cherry trees. I ended up watering about once every three weeks for them. Considerably more for peaches and apples.

Lot's of advice given here so far but no clue about the rootstock on your trees.
One reason for having so many different rootstocks is that many of them are bred for their ability to do well in different soils; sandy, loamy, clay, high ph, etc.
A ph of 8 is not what I would call "high alkaline". I have hundreds of fruit trees and they love it here with a similar ph.
To answer your question I would advise to use an organic fertilizer of your choice and when the soil gets dry then that's when you should water.

Check "DRY APPLES" on this site, it may help you for all your trees.
Everyone gave great suggestions which I am using.
Good Luck