Are you talking about the sealant that you use on the corners of the intake gaskets? To fill in the gaps on each corner where the gaskets meet.
You shouldnt have to wait for that to cure, it should be set up enough for use by the time you get everything else put togeather. All that does is keeps oil from spraying out the corners.
You shouldnt have to use sealant on the gasket faces, if you clean the surfaces good enough. If you use sealant on those, you are asking for them to blow out when the sealant shrinks.
I just done the heads on my 3.8 yesturday and was driving it by that night. With no problems or leaks.