Official comment
Thanks for the feature request! I can see how it would simplify waiting until Tuesday.
This is a related technique for some campaigns: Wait elements do have a day of week option that doesn't rely on a fixed date. A Wait element such as the one in the image could be set to wait until the day of the week is Wednesday, and then send the contact through.
You can combine these Waits with static dates, of course; a trigger for Dec. 1, 2020 could have a wait below it for "Wednesday", and the contact would flow through on the first Wednesday of the month on or after Dec. 1.
But we see the value in a day of week condition, so we'll leave this up to see how much interest is generated by this request!