The coming of Christ was first foretold in the Garden when Adam and Eve first sinned. The coming Messiah is prophesied all throughout the OT.
I’ve heard on this thread not a single Christian recorded in the NT found Jesus in scripture. So while the Messianic Promise of Gen 3:15 is well know, He wasn’t referred to as Jesus in Genesis so that must account for the confusion. Either that or the OT isn’t scripture either in reality or for the sake of this conversation. Apparently reading scripture can be idol worship as well so watch out for those Bible Studies!