Familiarity may breed contempt with people but is a necessity for survival in the cockpit. How long does it take to break the ingrained habit of reaching for switches on the aircraft you are current in to a new one. Then to operate the aircraft fully well it is not a WW11 aircraft with a few knobs and switches. I'll leave it to the more current members to make a professional estimate on time but given that once you qual as a fighter pilot there is still advanced schools of operations (Top Gun) to undertake to hone your skills.