If you want to know what the professionals do, just go to an orchard and asked them what kind of fertilizer they use and when they apply it. They will help you and you will get valid information. Another avenue would be to contact your farm extension office and ask one of the extension agents, helping people grow things is what they do and it is free.
When you are up to your butt in alligators, it is hard to remember your intent was to drain the swamp. Stay focused!