Bud break timing??

[PSU4ME]

Hi Folks,
I have four young fruit trees and am going to be aggressive with the fertilizing this year given last year they were planted as whips (and pruned severely) so this is my first full year on pushing them. Two each of apple and peach.

I want to get some fertilizer (stark Bro's tree pep) watered in about a week or so before buds start.

Anyone have a good idea or a "tool" that will tell me when bud break is in central MA?

Thanks!