Assuming that the BoS trials will be running, a detailed post outlining the exam dates and other relevant information will be made, so I would suggest keeping an eye out for the event that this is the case.
As far as I am aware, BoS trials are usually run at a specified venue(s) with the exception of last year's trials, which were completed online due to COVID-19. However, I think it would be reasonable to expect that this year's exams will go back to normal. With that being said, I am not involved in the BoS trials. It would be best to confirm any details with Trebla.
All the best!