This can literally be done. The only question is to what extent one has the capabilities to reach into the past intuitively in a way that the younger self will perceive the message? The problem is on both ends, whether the person of today has sufficient capability to launch an outreach through their non-local consciousness and whether the younger self will be reachable and able to perceive and understand the communication and be willing to take the advice and perhaps override the tendencies of that period of time.
This will not be as easy as it seems because people are not so easily manipulated. There are reasons people make bad decisions and it is often prejudice and deeply rooted emotions like fear that cause them to take a misstep. Simply running an idea past them subliminally via an intuitive message sent in this way will likely not have the force behind it that can persuade someone to change their thinking if there is a distortion going on at the time to confuse them and to keep them in ignorance about the true probabilities awaiting them in their future but, in principle, this can be done.