I took my son to his first game when he was a couple of months short of his 7th birthday.
The game was Brighton v Swansea. I should point out that the Goldstone Ground was a just a bus ride away from where we lived, and that we got half-price tickets from a promotion in the local paper. Excuses over.
It was a pretty dire game and I am glad to say it didn't initiate any ongoing support for the club in my son, although, to be fair, if it had done I couldn't have complained as we often bash on about supporting your local club, and my son, unlike me, is a Brightonian.
His first Palace game was against Leicester in 1996 - a 1-0 home defeat for us.
I finally got my daughter to a game when she was 23 years old. I don't seem to have much luck choosing the right game for an introduction to Palace - it was a home defeat to Villa in 2014, and she's only ever been back once. My son, although not an avid Palace fan, has since accompanied me on a number of occasions over the years but I think he has only seen us win on two occasions!