I always repot new plants as you can never trust the potting mix which has been used is suitable. It also allows you to check the roots for mealy bugs and treat them if needed.

SG,

Would you repot even in bloom? I ask 'cause the only cacti I grow are Holiday & I don't repot anything while in bloom since it can kill the flowers.

I don't know if the same is true of arid land cacti like Brian's.

Ya it may be best to wait until the blooms die off