Generalized message meant for nobody in particular.
You should likely let a human being grow and develop on their own naturally before you start adding outside stimuli. We’ve already messed with our children enough, our crappy food makes their bodies mature faster, our technology and environment makes them lose their imagination (and encourages bad behavior). And I’m sure there’s enough subliminal advertising going on already aimed at them. I wouldn’t want to bombard them with thousands of subliminal messages on top of all that.
Subliminals are like a vaccine, they give our brains the answer without having to discover it for themselves. Our brains should really be provided with challenges to overcome so they evolve on their own first. It’s how we evolve and grow.
So definitely don’t start subliminals too young. Instead provide them with enough brain teasers, and find a good school that stimulates all parts of the brain. And as a caretaker spend time with a child, don’t rely on technology to do it all for you.