Yes, correct you should wait, I can suggest you this, if you are anxious, get a IV gen - AB
test at the 28th day from the date
of your exposure. A 4th gen
ELISA test is a reliable test and a good indicator due to the simultaneous p24 ag & ab detection ability, if you fare negative on it you should be rest assured that your 12 week result is highly unlikely to change.
The best part is, a IV gen ELISA would cost a few bucks more than a regular ELISA.