Official comment
I'm not sure how we could accomplish this without an overwhelming number of choices in the drop downs, or multiple dialog boxes for what should be a simple function. For those type of scenarios you can probably just pick the date for the Trigger from the calendar easier than trying to figure out how to fill in the dialog boxes.
You can stack Wait elements for days of the week; in this example I'm using a Trigger for the 1st of April, and then a "Wait until Tuesday" (first Tuesday of the month). Wait a day, and then another "Wait until Tuesday" element is inserted for the second Tuesday of the month.


