this sun will fade (and turn to night)

It takes six and a half months for Steve to convince Tony to have kids.

Steve doesn't nag about it much at all, but he brings up the idea every once in a while. He prepares arguments that he never really uses -- because he'd never pressure Tony into anything -- but he does attempt to sneak them into conversations now and then. He feels guilty almost immediately afterwards, though, and he blushes and it's spectacularly adorable and quite forgiveable.

About the time it took, though; when you break it down, when Steve finally had the guts to introduce the idea to Tony, it took two weeks for Tony to take it seriously. Then another week to get Tony to stop freaking out and hide in the workshop.

That leaves five months and two weeks for Tony to process and accept the idea.