This is my first time replacing head gaskets on a chevy, but like you I had never heard of waiting but I guess it couldn't hurt. The one problem I had today was the felpro gaskets weren't marked front, top or anything but one side was rubberized between the cylinders and the other side was metal so I couldn't find anything on which side went up so just took a stab in the dark and put them in with rubberized side up. both sides other than that were identical, blue sealant and all. Hope I'm right heads not bolted down or torqued. So if you or anyone knows better please let me know.