How long after pulling you over can they give you a dui test that holds up in court

I don't know of a set time for administering these tests (possibly there is a state specific law in Colorado), but what I can tell you is that their timing can be very important. 

In order to convict a person of drunk driving the prosecution must prove that the person either drove at a time when their blood alcohol level was .08% or higher, or, were impaired by alcohol, i.e., under the influence, at the time of driving.  Therefore, the primary defenses to a drunk driving charge are that you were not .08% or impaired by alcohol at the time of driving.  Despite the fact that your test result may have been .08% or higher, this does not necessarily mean that you were .08% or higher at the time of driving.

The law is concerned with whether your blood alcohol level was .08% or higher at the time of driving.  A chemical test taken after you were arrested is only circumstantial evidence that must be related back to the time of driving. Depending upon when you finished drinking, when you ate, what you ate, your own unique physiology, etc., your blood alcohol level could have been below the legal limit at the time of driving and later rose to being above the legal limit by the time you were tested.  In such cases, it can be argued that you were not in violation of Vehicle Code section 23152(b), i.e., driving while having a blood alcohol level of .08% or higher.

What you need to do right now is to consult with an experienced DUI attorney who practices in the area where the alleged incident occurred.  They will know the courts and can best advise how to defend your case.

Best of luck.