Which calendar Mars Colonies will use?

As we are steeping closer to live on Mars, I am curious which calendar will we follow on Mars and how complex will be relation between Earth timezone and Mars time zone.

Also if use Mar Calendar (A year on mars = time taken by Mars to complete one revolution around the Sun > A year on Earth) then we will have to wait a little longer for birthday parties, just kidding.

Another Question is from where will the calendar starts? Mars year 01? and who will decide months names? Hehe.

I gonna tag Elon (yes the meme lord) and see if he get this figure out. Unfortunately he is not on itsMeh so I gonna use our friend Twitter. Will keep you updated.