I have a Shih-tzu x Bichon mix - I'm sure you didn't mean bison!
Until she was 10 months old, her hair was straight but after her adult coat came in, it's curly. Not kinky like a bichon's but curly. When I look at pictures of her when she was a puppy, I laugh because it looks hilarious! AT one point, her hair was so long (I like the long rock star look), she looked like she had bangs and the rest of the hair on her head was 'brushed' back - such an '80s look! That 10th month was hell, let me warn you, because the adult coat got so tangled with the old coat - I'd get rid of the mats and new ones would seem to grow. The cutting won't make the hair go curly but when her adult coat comes in, it may change. Just some advice, keep her coat short when she turns 10 months.