A photo is always helpful when seeking advice or help. Having dug a few bottlebrush (Callistemon) it would be best to dig in April or May next year and as they are at your parents house waiting until then should not be an issue.
Thank you for the information Sebastijan.
The summer period will be here in a couple of months and you have convinced me to defoliate this bonsai. It does need some pruning so I will take the opportunity to do that at the same time. I will post a photo when it is leafless.