When can I prune fruit trees?
It is best to prune and limb up about Halloween so you don’t encourage new growth now that will not be hardy enough to withstand the winter. The tree will be using energy it needs to survive the winter. Also don’t fertilize trees now for the same reason. If it is a blooming tree, the best time to prune is within a month after bloom if you want the pruned branches to bloom next year.
Here are a couple other links that provide details for the peach tree you have and fruit trees in general: