My advice would be to make blueprints of the basic stuff; anything like a steel furnace array or a set of electric miners etc., figure out once, and then make a blueprint of it. It's way easier to place stuff down to fit a blueprint than it is to just place things down off memory, even for obvious or simple things, and that gets you to the point of automating construction bots that much faster.

I'd say it's entirely reasonable to have bots within four hours of starting the game, even if you don't really know what you're doing. And the bots of course solve the 'single unit' problem.