
I usually recommend terriers are brought into me at 6months to see if the coat is ready to strip, some are, some arent, also depends on the breed/lines etc.
But usually I strip Borders at 6months, as there all pets, not shown, but my own I start at 4-5months.
My friend shows cockers and she doesnt strip them til 9 months , only tidy's them up before hand.