If one goes by the usual yardstick that most of us don't retain very much in the way of detailed memories of "ordinary" experiences before age 10, that would only take him/her back to the latter half of the 1930s.
My mother is 89 and the bulk of her youthful memories start around the final year or so at primary school. I'd say the same broadly applies to me.
I did become somewhat obsessive about railways from about age 8 and recollect more about that than pretty much anything else that was happening at the time........ .
Typical? No idea.
I don't know. By contrast, I do have quite a few vivid memories (not false memory syndrome either) from age 4-5. I remember seeing the pictures of the Hixon disaster on the front page of the Express and Star a few days before my 5th birthday. On a much happier note I vividly recall seeing the Manchester "Blue" Pullman running down the Trent Valley line towards London which must have been in about 1967 as the loco-hauled Manchester Pullman began in late 1967. I can remember lots of countryside walks with my parents along the canal watching the new electric trains, and then my first days at infant school which was next to the railway, again loads of memories of early AC electrics, mixed livery trains, loose coupled freight and the odd-ball trains like the afternoon "Brickliner", which often co-incided with pre-hometime story reading sessions outdoors on fine days, double headed by two very noisy Brush Type 2s being thrashed. The sight of these two "rare" diesels bellowing past whilst Mrs Niblett tried in vain to tell the story above the racket is still clear over 50 years later. Mrs N., God rest her memory, gave up trying to get me to concentrate on lessons outdoor in the summer when there were trains about, she knew it was a thankless task.
In fact it's these retained memories, vivid and clear, that are driving my principal modelling interests. I suspect the reason why they have become rooted is it co-incided with possibly the happiest period of my life, and the fact that I have a very good, highly developed visual memory. I hated secondary school, and the death of my mother in 1973 when I was 10 meant that the 70s are less vivid, mainly because of school and home life. That said, despite the 70s being less happy I do have an obsessional interest in 70s design and architecture so perhaps I don't have such a downer on that decade after all.