Age 4. I went on my very first roller coaster at Disney World called the Tower of Terror. What an emotional day. I remember it because I was so excited all day long until I finally got in line and then I remember being scared and crying. I tried to convince my dad that I was too young and not ready, but he told me he knew I could do it and I remember thinking that if he sat next to me, I would be safe. We went on the ride and I loved how fast it went. The experience was so much fun that we rode it 6 times in a row because the lines weren't very long. The extraordinary circumstances that make it memorable are the fact that it was my very first roller coaster and I had so many emotions toward that fact. In some ways my personality is the same. I still love and look forward to trying new things, especially ones that give an adrenaline rush, but I am not so easily convinced by adults. Just because my dad sits next to me, I don't think I'll be 100% safe. I still have similar emotions towards trying new things but they are much less intense.
I have another early memory besides the one I posted and it is similar to yours. I have an early memory of being a cedar point and at the time I did not enjoy going on roller coasters. I was probably about 5 and I would only go on the indoor roller coaster at cedar point.
