According to Mr and Mrs Genghis Sr. my first airshow was Leuchars at about the age of 3. Apparently I slept through all the jet noise, then woke up and started crying as soon as the noise stopped. Strangely, I still feel the same when aircraft noise stops, particularly if I'm still flying.
Earliest I can remember with any clarity was an Old Warden air-day when I was about 9.
G