I guess the result availability depends on test centres as they provide official results to be previewed on BC/IDP website. If anybody notice, the test results for the date of 15 Dec is available for preview on British council’s website but not every applicant can see their result. My test centre explicitly stated that ‘due to holidays season, test results will be available online by Jan 2’. Apparently, if your test centre has bot given such kind of info then your result should be available by tomorrow, 28th Dec