dont they just loo so cute and innocent at this size......they have some tiny ones in at my lfs at the moment, they look well different at that size!
i've had mine around a year, got it when it was around 5 inch and know its about 6 inch and seems to have stopped. so i guess they get to around 4 inch reasonably fast then slow down, i've never seen another as big as mine though so they may not all reach that size!!
Dave