Steve tries to wait until it seems like Tess will be up to talking; he also tries not to put this off so long that it'll seem utterly rude. He ends up sort of splitting the difference, probably - Tess will definitely be well over any death toll by the time he knocks quietly at her door one evening, sometime between the end of dinner and "too late for polite company."
spam, maybe about a week and a half after the end of the flood?