Cherry leaf spot can infect the small bract leaves the trees open first in the Spring. Here is link from Michigan State University on how these early infections with leaf spot can be a problem.
I have tart cherries and they get cherry leaf spot. I have sprayed a mixture of a Captan and Immunox or used Daconil (chlorothalonil) depending on the year and the time of the season. And as Mamuang mentioned pH is critical for spraying Captan.
I spray in the Spring one or two sprays between bud break and the popcorn stage. Then after petal fall I do additional sprays. I find the Spring sprays to be critical and the spray intervals also to be important. From my experience if even a small amount of leaf spot is visible on a tree the difficulty in controlling the leaf spot increases dramatically. I don’t see large differences in control between the Captan/Immunox mixture and just using Daconil.
But Daconil can’t be used between shuck split and harvest which is a disadvantage. However, Daconil can be used for peach leaf curl and used on many vegetables and ornamental plants so many people find Daconil to a useful fungicide to have in addition to Captan and Immunox.