I probably got a clear head around 18 months in respect of things I was familiar with. Eating, bathing, turning up for work, getting dressed, meeting friends etc. Then at about 2-2.5 yrs I went into a trainee job at a much higher level than anything I had done before. The fog was bad, it took three months of serious effort, working 6-7 days, learning the technical side, and then finally talking to customers and answering their questions. There was a big change at that last point, and I emerged from the fog. Growth and learning were not easy, but worth it.