I do not know if they use "special" turf at Stamford bridge that needs 2 weeks but I was in the San Siro before Christmas. It was about 3pm'ish on a Friday and they had 1/4 of the pitch relayed at that stage. They worked through the night and had it ready for a Sat evening kick off. A cup game had been played on it the Wednesday night so effectively they had 3 days to do it. I was at the game on the Sat night and the pitch seemed to hold up well.