Is the goal to meet others elsewhere, or help your own team recruit? The optimum for the first would be during a global school break time, whereas the second would be near the start of the school year while most schools are session. Much different goals. (I'll discuss the latter here, as IMHO it could help the team more...)
I'd avoid a particular day of the month (e.g. "the 13th") because 2/7 of the time it would fall on a weekend, and no one at school would see it. Similarly, I feel we should avoid Mondays, as a lot of holidays fall on it.
If monthly, how about the "Last Friday of each Month"? Friday is the "casual day" at a lot of companies.
If you want it once a year, I'd suggest "the last Friday in September". Several reasons:
- It's coming up soon (we can do it this year);
- Most schools are in session that day every year;
- It helps team recruiting by advertising their presence near the START of the school year yet AFTER the "start of year confusion" settles down; and
- It gives you an excuse to "encourage" your industry supporters at "Casual Friday" companies to wear theirs as well to drum up more support for mentoring.
What is the goal of the Shirt Day?
- Keith