I do a lot of work with systems that are Europe based and all of them have weeks start on Monday and end on Sunday (Which I rather like... The weekend, is the weekend, not the week book ends)
Without this capability I'm always fighting the Timesheet and can't use "Previous Week", for example. I always have to use a Custom and set the begin/end dates. I first looked for that feature in Settings -> Display. I don't know if there is a better place.