Leaving aside the legality or otherwise of taking the skill test before a solo flight, I don't think any student who has not flown solo would be capable of demonstrating the mental attitude and command capability that is required to pass the test.
So I agree with BPF - asking the question demonstrates a lack of awareness of what's involved to the extent that taking the test would be pointless.
http://www.av8n.com/how/htm/decision.html#sec-decision