I might have made this up as well, but I have a very distinct memory of basically suddenly becoming conscious at around being 3 years old. I woke up from a nap and for a couple hours or possibly days, I wasn't sure whether I was dreaming or the world around me was actually real. After a couple of days of waking up in the same environment, I eventually accepted this to be reality. I of course don't remember everything from this point on in my life, but it really felt like the first time I was able to explicitly think about stuff.