February 1st lands on a Monday so this month will be easier to keep track of in terms of 'Monday-1 day, Tuesday 2-day, Wednesday 3-day, Thursday 4-day, Friday 5-day, Saturday 6-day, and Sunday 7-day. Yes, Sunday is officially the first day of the week, but with the work week or weekdays being the busy days for folks, Monday-Friday, it just kind of makes sense.
The Jewish tradition marks sundown on Friday as the start of the Sabbath and that continues through Saturday sundown (and Sat.