order nr is not the serial number and there will be just 500 pieces of that model as I know.
It is good habit to use just one counting series for one model - f.e. Zixen trimix - 0 to 3000, regardless the movement (and you have choice of two movements). Another zixen DSR1000 has again - 0 to 3000... etc...
use one counting series for ALL models - f.e. Armida - if you buy specific serial, you cant have that serial with next model of Armida. So newer models have higher serials.
I know, all about that serial numbers is just pathetic thing, but some unwriten rules should be followed :)
Give me one example of any brand which do it this way like Olivier!
But as I said, amazing watch and will worth much more than they cost, underlined and... period!