Things have changed fast. In London, 86.4% of COVID-19 cases with known S-gene status have s-gene target failure[1] which is a marker of Omicron (albeit with pending sequencing confirmation for certainty[2])
[1] https://assets.publishing.service.gov.uk/government/uploads/...
[2] https://www.who.int/news/item/26-11-2021-classification-of-o...