How many weeks documentation will the auditor required to see.
It looks like you can undertake the certification as a standalone audit, but as with the main BRC standards there is no specific minimum defined but does state that: It is at the discretion of the site when they wish to invite a certification body to carry out an audit; however, it is unlikely that full compliance can be satisfactorily demonstrated at an audit undertaken less than three months from commencement of operation."
The primary consideration behind this is for new sites, to ensure that they have been in operation long enough to have sufficient records to allow them to be properly audited, but the same arguably applies if you are creating a new set of controls/system and need to be able to demonstrate to an auditor that it is working. Unsurprisingly the standard also suggests that the self-assessment tool should be used and an audit booked once any nonconformities identified by this have been addressed, before booking an audit. Nonetheless it's probably worth speaking to your certification body to get their input, since they'll be the ones conducting the audit.