4 days after exposure is way too soon. The test may come back positive, but that could mean that you were exposed in the past and didn't know (sometimes you do not have symptoms of HSV infection). If the test comes back negative and you are still concerned get tested again in 3 months.
Four days after is too soon. Herpes antibodies can't be found in a blood test that soon, if the test turns out to be positive, transmission has happened earlier. After three months the result is much more accurate, although not final. Sometimes it will show up later, but it's not likely.
The best bet is to take a culture from a lesion, so I advice you to see a specialist if you develop herpes blisters. It's a more accurate way to verify both herpes type and location.