The Fourth Doctor knew his time was running short when he spotted the Watcher during the serial Logopolis. While he did not directly hint (until the very end) that he knew the Watcher's purpose, it is inferred that he knew exactly that his time was coming to an end, which is why "the moment had been prepared for".
I am an avid fan of Doctor Who, Video Games and WWE Wrestling who is a 12 year medically retired veteran of the U.S. Air Force.
I've been married for 14 years with two children, 10 and 8. As a stay at home father, I find myself with copious amounts of free time and have taken to writing as a way to give me something to do. I currently reside near Kansas City, Missouri in the United States but am originally from Chicago, Illinois.