In my direct personal experience, for me it was 1969 during my first major gig. I remember one project, called the March 1 system, that slowly came into being sometime that October, if my memory serves me correctly. There was tension, of course. This was exacerbated by having to work nights to get access to the system to continue development.

I eventually learned, when asked for a "quick" estimate, I would give something drastically longer than I knew would be accepted. I said "But I can give you a better estimate if you give me a few days to do a better plan." This always got me the extra time to provide an estimate.