You cannot, repeat CAN NOT judge those tans now. They are way too young. Typically, even though I show juniors, I do not make any tan judgement at all until 3-4 months old, and then I still keep most of them until they are 6-7 months old, sometimes even a year.
It depends on your bloodline. In tans, it varies widely. Example. Nearly everything I've had from Jodi Hartmans line has been outstanding as a junior, then got long in the shoulder and went to crap as a senior. The Mark Beckett buck I have was outstanding from the day he hit junior prime.
The Morgan Shutz stuff I have I never saw as juniors, but seem to hold senior prime well into maturity and beyond.
The Joe Kim lines, which is primarily what I have are sloooooowwww developers. I never judge early. So many times, I've kept back a junior for some reason, and shown and they place last and last and last, until they are grown. I have buck that placed last or second last all the summer he was a junior. They when he was right at a year, reserve in show.
I have another buck, that was actually my friends, and he was a yuck junior. For some reason, my friend held him back, put him in a cage and forgot. He started showing him at a year. Now I own that buck. He has 20 something legs and 6 or 8 best in shows.
I also wanted to add that the Joe Kim lines tend to have ultra wide butts and you have to cull for that and breed to something to counter that particular characteristic.
So in conclusion, way too young, and it depends on your lines. Tans are a hard breed to learn.
You said you weren't certain what one should look like. Look at my website for examples.