How many miles on an OCI before doing a UOA?

Richmond, Va
I have a 2001 Pontiac GP 3.8 non sc. After reading up on this intake gasket problem I have decided to do my first UOA to see if there is any antifreeze contamination. W/ just ove 70k on the car and 3k on my current oci, I go 5k most of the time, is it too soon to check for contamination? I can take a sample by removing the filler neck and using a turkey baster so to not have to do a full oil change. What do you guys think?
I've done UOAs @ 1,700 mi, 2,600 mi, and 3,000 mi. They've all read about the same. I'm supposed to get my 3k UOA today, still waiting for it. I use synthetic Castrol 0w30. There was a UOA study done awhile back where the guy took an oil sample with a pump every 1,000 miles. So I wouldn't have a problem doing a UOA now.