Bic DuFour monster... was more of a boat than a windsurf board.
Found this image on the net:
First proper jibe was on a 3 meter Bic FunBoard which had 3 fins in the back... a bit like a modern Thruster without the performance.
But to be honest even the pros don't nail a carving jibe 100% of the time. Unless you are in dead flat water there is so much variation that can mess up your jibe.
Try a modern free ride board. They are quite forgiving.
Most important things to remember during a jibe are shifting the sail with enough dedication at the right moment (most people release the sail too late) and the position of your feet.