Or until they feel good in your hands. Although stand in your boots and click into your skis to check the height. But watch the 4frnt tech talk on it, my brother got a pipe cutter for 7 dollars and it worked fine.
Hold the pole upside down and put your hand under the basket, cut it so that you have a 90 degree bend in your arm. Short poles were cool like 3 yeras ago, now all the trend followers are doing it. Shorties work in moguls,. Just remember the shorter the pole the easier it is to stab yourself in the stomach/face/chest.... And put baskets on please, no one needs a spear in the head.
I keep mine about 5cm longer than the average guy, I like to push with them through flats and use them for touging where you need longer poles cause of pow.
You guys can't make some cut in the leather or something? All you'd need to do it make a line so a pipe cutter/hacksaw blade could get right to the metal. Then cut, remove a bit more leather and slide the grip back on.