Another question about Herpes (HSV-2) blood tests-?

I keep seeing you're supposed to wait several weeks to get the blood test so you can have a detectable amount of antibodies built up, but what I can't find is whether that's several weeks from when you were possibly exposed to the virus or several weeks from when you noticed physical symptoms. If I was in fact exposed to this then it's been probably 4+ weeks ago, but the physical symptoms started about a week ago. Appt for the blood test is 1 week from today.