It was sometime in the '50s, ORD/PBI.
Since there were no frequent flyer programs back in the day, I am not sure which airline I flew, but I remember the new red coat that I wore. I thought I looked so spiffy.
Interestingly, my flight habit of alternating between reading and looking out the window, were exactly the same then as they are today.
I also remember the first time I sent my first-born (age 9) on a plane by herself SEA/SRQ to visit my sister. She thought she was really hot stuff, until she found herself seated next to a 10 year-old boy who was flying from Capetown to Sarasota. He had had to spend a night in London with some flight attendants. I am not sure how that worked, but that is the story he told my daughter. She was impressed.