flour, give or take, before it's ready to rise. i can usually mix in the fifth, the sixth, and sometimes even the seventh cup using a wooden spoon adding the flour one cup at a time and thoroughly mixing in each cup before adding the next.
somewhere around the seventh cup, the dough will just get too stiff to keep mixing with a spoon. it's time to turn the dough out onto the mixing board. before i do that, though, i put another cup of flour onto the mixing board and spread it out to make an area large enough to turn the dough out onto and flatten it out somewhat. 