For the first 3 years of DS life this was the advice I received from HV and doctors, that if I do it before he's ready he'll be at risk of all of the above.
Then at his 3 year checkup the HV said why haven't you started potty training yet and I said oh we kept trying but he wasn't getting it and wasn't showing any signs of readiness to which she said: why are you waiting for signs of readiness, that's a myth, they don't need to wait until they're showing signs of readiness.
DS is autistic and was diagnosed at 3 and a half so even if I had tried sooner and ignored advice theres no guarantee he would have been toilet trained anyway, but the changing advice felt practically overnight.
I've been on a few ERIC webinars since for kids with autism and the advice even there is very contradictory. Always change in the bathroom so they associate the bathroom with where to go, but don't change them in the bathroom if they've got sensory issues with bathrooms, take them out of nappies completely so they learn they have to go somewhere, except if they'll only go in nappies and then do not under any circumstances force them to withhold, always be consistent and lead the charge, but always give them autonomy and be flexible if it isnt working, don't wait for signs of readiness just create a routine unless your child is PDA and then the expectation of using the bathroom might become too stressful.
It feels to me like whatever you do or don't do, you can't do right for wrong.
Sorry, I know this is a slight derail and very much a rant, and appreciate that DS is SEN and therefore the approach was always going to be a bit different, but I just feel flustered about the advice that always seems to change and at the time of its delivery always seems to be "the correct advice" until something else comes along to debunk it.