For example, my mom potty trained me using a coffee can and newspaper on the floor. I have vivid memories of using both, even of words she said to encourage me to use them, having my diaper taken off and turned loose in the kitchen to do my biz. Her praises for getting it done, etc. We didn't have indoor plumbing or indoor running water. I was potty trained at 11 months using her methodologies but I don't recall being that age i.e. I can't link to age prior to 18 months.
I also have a very vivid memory of my mom washing me in the ditch before I could even walk. Evening. Dark. Full moon. Right side of driveway at the farm house area. Weeds and cat tails in the ditch, trees in the ditch further to the right. My mom carried me out there after she finished washing clothes in the shed next to the barn, which I also remember. Vivid as can be.
It was vivid I suspect because the water was cold and that may have contributed to the memory retention. A lot of times the external stimuli contributes to the memory being retained. I doubt I was much older than 7-8 months.
For example I have an exceptionally vivid memory of getting my fingers of my left hand slammed in a back car door before I was 2 years old. That one is permanently stuck in my head just as clear as a bell and just as clear and sure of a memory as I'm sitting here typing the memory. It was at one of my aunt and uncle's wedding, front of the church, my dad had put me in the back seat, riders side, I was standing on it and put my left hand on the door post to catch my balance just before he shut the door. My folks were talking outside the car with other relatives. I was screaming bloody murder because my fingers were shut in the door. I very vividly remember the pain shock when the door slammed shut. One of my uncles said "why is he crying" and then said "Oh my God, his fingers are shut in the door!" It seemed like an eternity to me, but it was probably just a few seconds. Yeah, I remember. I remember being glad they opened the door, and the throbbing pain in my fingers all the way home too. And I know I was less than 2 because of their wedding date. When I told my aunt many years later, as an adult, about the memory she said there is no way you could remember that. You weren't even 2 yet. The uncle who opened the door and was there when we were talking about it had forgotten about it, but recalled it when I recounted the details and confirmed it had indeed happened just like I said. I can still hear him in my mind, vividly, recognizing and exclaiming that the door was shut on my fingers. My dad didn't even recall it. My mom had a faint recollection of it. My memory of it however is and remains exceptionally VIVID. I'd liken it to being carved permanently into my mind.