Is it ok to substitute a birth control pill for one of the sugar pills in order to change the start date of your period? For example, if you normally start a new pack on a Monday, is it ok to take your first real pill on a Sunday (instead of your last sugar pill) so that your period will start earlier in the week? Will this increase your chance of pregnancy? I know it's bad to start a day late, but I hadn't heard anything about starting a day early. Thanks.