I think prices start to reverse downhill by Friday afternoon like around 2pm US NYC time so you must decide to exit by then cause it will turn low so if you have been waiting all week then its time to sell for profit or if all day then its time to sell by then. By 2pm most traders close off their positions therefore lowering volumes and demand and therefore price as well and so you must take profit by then but you can buy low on late Friday afternoon and wait until next week to sell it off. What do you think?