How long should I wait before I tack up a vapor
barrier and screw on the drywall???

The wood won't be fully dried for about six months, assuming normal
humidity.

I currently have an oscillating fan blowing on the
framed walls. (Its been 48 hours, wood still seem very damp).

The Tapcon screws worked wonderfully, but I'm
wondering how they will do when the wood starts
to dry....

The Tapcons will do fine, Put up drywall whenever you're ready. You
could have purchased PT lumber with a lower moisture content, but it
likely wouldn't make a difference anyway.

Jeff