System Administrator Appreciation Day is on the Last Friday of July.  Always has been on the Last Friday of July. It has never been on any other day of the week or any other month. It has never been on a Saturday.  Whatever day the last Friday of July is in your own country, as long as it is the Last Friday of July.  Sysadmin Day is a 24 hour event, for the entire Last Friday of July. From the first minute of Friday, to the last minute of Friday.  Celebrate Sysadmin Day in your own local time-zone, for the entire Last Friday of July. A “day” is defined as the twenty-four hour period starting at 12:00:01 a.m. and ending at 11:59:59 p.m.

More info here if you like