When I took my CPL(A), my whole class bought Bristol together, since back then there were no rules about how many log in you can have at the same time in one account. Today, 2 persons can't log in at the same time in 1 account because that might get the account-owner banned, so don't share your account with anyone!
Now I'm in the last stages of my ATPL(A) theory and during the 3 times I have bought Bristol, I did it just 1 week before the CAA exams and it has worked out nice.
Don't forget to use both Version 2 and version 3 of Bristol. You can access both versions under the menu.
Peter H