I’m 53 yo and had this problem all my life, and nothing really solved it. But I will say that the most useful life hack has been to lay EVERYTHING out the night before. THis didn’t really solve the problem of a glitchy brain that loses track of time. It just helped me get out the door super fast so as to minimize my tardiness.
And then I bought a smart phone which has almost completely solved my problem! I enter my destination into Google Maps (every day, even though I obviously know where I’m going). Not only does it tell me how many minutes it will take to drive, but the exact hour and minute I will arrive. I keep my phone by me as I am getting ready to leave in the morning and constantly refer to this arrival time. This works so much better than just setting a random timer that doesn’t connect anything for me. Somehow, seeing my arrival time in black-and-white overrides my brain’s time-glitch. (My brain’s plan is to teleport myself so as not to be late!)