its about 3-3.25 in. When I got my Red devil they were both about 2.75-3 in. I just returned my red devil about a week ago due to its relentless chase of all my fish and it was 4.5-5 in. and about .75 in thick. Im guessing the difference in species equates to the size difference.
Rose queens don't start off red or "purple". They start off some variation of color between the Amphilophus x Vieja type it's crossed with. As the fish matures it will "peel". Not all fade at exactly the same time or age. Some take longer than others. As for shape, that's completely dependent on genetics. Some will look more Vieja, as most rose queens do. Some look more Amphilophus, retaining a more narrow head/mouth structure.
IMO it's still too early to tell. The fish is just over 3" you say. Give it some time and see what you get.
Why not post this in the hybrid section? There are far more people there with experience to flowerhorn types than the folks that tend to hang around SA/CA boards.