I understand the want to level as Prot, as Prot leveling ain't too bad, but to be honest, I don't see much reason to touch the Prot Tree until you get, at the very least, Avenger's Shield, Shield of Righteousness and maybe even Hammer of the Righteous. Those 3 attacks, along with Blessing of Sanctuary is what makes a prot paladin, a prot paladin.
Without those, you will level very slowly and could easily get burned out. Your first respec only costs 1 gold, my suggestion, is to level as Ret (go down the Ret Tree, trust me) until Level 60.
Once you hit Level 60, you have all of your signature moves that a Prot Paladin has, grab yourself a good 1h weapon and shield, whack at some mobs to skill it up (it won't take long), and then level as Prot.
Doing Ret Pre-50s is a heck of a lot faster and easier than trying to AoE mobs as Prot, when you are missing a large portion of your main abilities.