Good point, when I wrote down the predictions, I just used my usual unrealistically optimistic estimate of: "This is in principle doable in this time and I want to do it.", i.e. my usual "planning" mode, without considering how often I usually fail to execute my "plans". So in this case, I think I adjusted neither my optimism, nor my plans, I only put my estimate for success into actual numbers for the first time (and hoped that would do the trick).