Lofus, if you are adding a tang, most suggest to add it last.
However, I don't really see anything on your stocking list, that IMO most tangs would bother. Plus, then you may be in big trouble.....QT or not...
You will have to watch your QT water parameters really closely in such a small QT tank, because tangs need to eat a
LOT to build up their natural immunities.
I always found a chromis made good company for a fish held in QT, they seem to be less stressed with a companion.
That all said, it's probably not really exactly what
I would do in every case.....
but I have been very
lucky.....be sure you get a plump tang that is eating like a hog.