Hello
They look very young. Young discus don't show their full colors for a while. The discus you purchased seem to be of fairly good quality. They are a little skinny but all in all look good. It seems you have either kept discus before or have done some reading which is good. You should go to the discus for beginners section and watch the video on keeping discus just as a refresher. Some things have changed in the last 10 years or so.
As to the fish
Your tank looks very clean and well prepared for discus. Keep up on those water changes and they'll grow up for you quite quickly. It looks like you may have a "Snow White" discus in there. Which is an all white discus. Some of the others are very hard to tell by the pictures. If you see them showing more pattern once they've acclimated post those pics. I'm sure people can help