Yosef Karo, Shulchan Aruch — Yoreh Deah 395
“ Once the consolers stand (in the presence of) the mourner on the seventh day (ie. they get up to leave the shiva house) , he is permitted to do all of the things in which he is prohibited within the (first) seven (days) , for part of the day is as if it is the full one, regardless of whether it is a part of the seventh day (it is valid) , or a part of the thirtieth. ”
