# strptime
start_date = datetime.strptime(start_date_str, '%Y-%m-%d')
day_name = datetime_obj.strftime('%A')
%a
: Sun, Mon, Tue
%A
: Sunday, Monday, Tuesday
%w
: weekday as number (0 is sunday, 6 is saturday)
%U
: week number of year (00, 01, ... 53) - Sunday as start day
%W
: week number of year (00, 01, ... 53) - Monday as start day
%d
: day of month as zero padded num (01, 02,...31)
%S
: day of year as zero padded num (001, 002, ... 366)
%b
: Jan, Feb, Mar,..
%B
: January, February, March, ...
%m
: Month as number (01, 02, ... 12)
%y
: year without century (00, 01, ...99)
%Y
: year with century (0000, 0001, ... 2013,2014,..9998)
%H
: 24 hour hour (00, 01, 02...23,24)
%I
: 12 hour hour (00, 01, .. 12)
%p
: AM or PM
%M
: Minute (00, 01, .... 59)
%S
: Seconds (00, 01, ... 59)
%z
: UTC, EST, IST, CST... (empty if object is naive)
%%
: The % character