Design doc time then! Sit down and write out the first good idea that comes to your head that you think you could complete in 1-2 months :). Write it out in as much detail in design doc format as you can. Take a whole day to do it. Flesh it out. Eat. Come back. Flesh it out more. Poke holes in it. Fix the holes. Eat again. Come back. Read it, ponder it, rewrite it if you have to. Sleep. Wake up. Re-read it. Still a good idea? Get to work and we’ll see you in 3-6 months (note how the amount of time has tripled from your expectation).
