Cara had done most growing by 6 months - she added maybe another half inch in height after and 'filled out' between 6 and 9 months (mind you 'filling out' is hardly apropriate, she is quite a slim mini) I reckon Mo has half an inch of height MAX and may fill out a little more although she is already stockier than Cara. Mo is 7 months.
Dannie is right - 9months they are fully grown physically. Can take up to 2 years I'd say for them to reach 'adult' temperatment (adult used in the loosest possible sense of course)
Cara and Mo, two black mini's and Molly a black & white Heinz 57 all served by Elaine, the cook, poop picker, and chief toy thrower.
I live by the Mini Schnauzer code; when in danger or in doubt, run in circles, scream and shout!