I always wondered whether my memories were unusually early... But what I heard agrees with what Kaybee said.
But here I'm somewhat in the normal area. For me the dating is relatively easy, since I moved 3 times in my life (always into another town), the earliest one being when I was 4.
So everything taking place in different places of that town must be from when I was 4 or younger.
Furthermore, I remember things that my parents can easily date.
My first memory is when I was somewhat around 2 years 5 months. My parents wanted to buy a new car, so my father went to a store to look at the options and took me with him. I can still see some faded images of that store and my father sitting in a car. I also know that I wanted a red one, and that my parents took the one that I liked best (which was red). For years I thought that I had had a decision in which car my parents bought...
The second one is when my father picked up my mother and my newborn brother from hospital, and again took me with him. I must have been 2 years 10 months at that time.
And then there's one that I only recently discovered to be a memory. I remember sitting in a car, with some baby in a baby basket next to me. I didn't know who that baby was.
Then, a few months ago, I asked my mother whether my brother's baby basket was dark blue with a pattern of white dots...
There are some memories, however, that also must have happened before I moved and that I cannot date.