Typically, in order to get larger peaches, the trees need to be thinned. Deciding when to harvest peaches is a matter of personal preference. While most people prefer tree-ripened fruit, but fruit at this stage has an extremely short shelf life. Therefore, it may be better to pick the fruit two to four days before it is fully ripe. Here are some things to look for when harvesting peaches: When the fruit is easily pulled off the twigs then it is probably ripe. You should feel a certain amount of movement when you press in to the flesh of the peach with your fingers. When peaches change from green to an orange tint, they are nearly ripe. Ripe peaches will give off a pleasant, peachy smell.
These articles should help you with growing and harvesting peaches: https://www.gardeningknowhow.com/edible/fruits/peach/peach-tree-care.htm