There is a fascinating record that the Woodland Trust are doing on when they first flower here https://naturescalendar.woodlandtrust.org.uk/analysis/species-and-events-map/?type=3&speciesId=161&eventId=3&year=2009 move the slider at the bottom to see when they start to flower over the country (you can also change the year at the side - I linked to 2009/10). I usually judge now from the photographs people are posting on #wildflowerhour on Twitter and I would say they were mainly just starting to flower in the last week or so. My judgement of time is not very good, so that I can never remember what happened last year unless it's written down, but it does feel like we haven't had a proper cold winter up here in the north east.