It’s all arbitrary, isn’t it? Who says you have to celebrate it on the actual day? You can party on any day of the week you choose, though legally and officially it may be on a Tuesday.
I was born on a Monday, and am turning 20 on a Friday… this should be interesting, considering what I want to do for my birthday. I wonder if I’m going to be able to convince a driving friend to cart me and him/her/them all the way to the other end of Florida for a weekend of Renfaire. It’ll most definitely be fun if I do. 
I loves me some Renfaire!