Sorry I know I just double posted
My experience getting this title will be different from most people but I think I can give you some idea. I had done all of the quests on horde side that gave rep for those factions and most that had not. around 430 total. I had also done all of the lunar festival quests to honor your elders. If I remember correctly each one gave you 75 rep to all factions. I also ground out a lot of chens empty keg, so if you are not doing that (which I would not recommend) then you will have to make up for both the lunar festival and the chens.
I got mine at around 130 or 150 quests complete on the ally side. There are over 500 on ally so I would assume that you should plan to do all of the quests on the horde side, and i know that you can hit exalted with 2 of the factions depending on your home faction, and revered with the others, just from ally alone. So you will probably hit exalted with all of them well before finishing up the 500+ quests on the ally side.
Maybe someone can give you a better idea if they had done it without doing lunar festival quests and chens empty keg. Hope that was helpful though.