The thing is that to be honest that Length is of no importance to "Breeder's" will all the records and information we all ready keep up with to try and compile a growth chart.
It would require more than one breeder keeping a large number of animals from birth till adult and keeping the growth records month to month as well as size and weight of prey offered for each snake.. that's allot of information.. just to figure out something that to be honest isn't that important..