can you?

Can you Dna test around 8 weeks or is it 10? I am currently 5 weeks pregnant According to the calculate thing I used. If anyone can help me figure out a few things that would be extremely helpful!!! I can't remember he exact dates I had sex with each guy (as in only 2)  but I think one of them I had sex with on Feb 5th or 6th,
And the other I believe it was before that sometime! My last period was January 21st of 2016 
Can someone maybe help me figure out who the dad may be ? Not really good with this kind of stuff.
Please don't judge :( we all make mistakes