Technically one can ask what came first?..the dimensions or the Maths?
Some of the abstract mathematics of string theory do not conform to our everyday experience, for instance in order to accomodate more than the usual three-dimensions, there are Mathematical extensions..all the way up to infinite (Wittens latest paper).
Some time ago there was a general concensus that 26 dimensions was pretty much suitable for the avialable 'string' Mathematics, but if the current trend continue's then there will not be enough Dimensions in our Universe to accomodate the coresponding predicted Mathematical Dimensions!
Of course the spacetime dimensions (theorized as 9+1 until Ed Witten thought of another dimension, and then 9+1 became 10+1 spacetime's).
There are about 12 Time zones graphed onto the surface of the globe, this is for each individual nation to define their own existence with their neighbours and stops Airlines from landing planes at the same time and such!, this is a human construct for ease of correspondance, it is not a consequence say of the proximity of the Earth within the Solar System along the Galactic Arm!