The mandatory date is 24 July, but people near me seem to be treating it as its safe to not wear masks till this magic date.
I assume the delayed date is to give people time to get masks but Id have preferred a message of, we want you to wear masks NOW, but we wont start fining people till 24th to give you time.
I think months ago, worries about supply and hoarding was a very real and present concern. Since that time it's been 'face coverings' rather than masks, which allows the mask supply to be maintained better.
I do think the accompanying health message is poor. It should emphasize that virus circulation is low so any incremental gains really helps keep the virus at bay and face coverings is part of this. Secondly 70% of all cases are asymptomatic, in Jan-April it was thought 20-50%.
Not sure whether any of the government's recent thinking is influenced by Imperial group on R. It was 4 and they think it fell to a lower level after 'lockdown' of around 0.5 rather than 0.7 to 0.9. Again incremental gains, if this is true various additional measures to reduce R make a big difference over 2-3 months before the winter surge.