I think that their strategy is more smoke and mirrors - they're looking for the massive uproar so that the public understands that what we're facing is the real deal and will accept the harsh restrictions to freedom better once they have to be made.
The damage caused by an extra day or two of waiting will be small in comparison to the benefits of good compliance.
Plus don't forget that it's the weekend. No schools. The schools won't be open on Monday.
Dominic Cummings and his team are sharp and extremely good at manipulating the exact group of unthinking idiots who would otherwise ignore curfews and restrictions..
I should also add: all of the other Western countries are doing the same thing, UK included. Do whatever is possible to keep the health system working until. Eventually you get herd immunity either via people getting it or a vaccination.
I don't think the risk of this pandemic approach is worthwhile, especially given how poorly the EU is doing in general. Terrible economy, catastrophic pandemic response, and the symbolism of countries closing borders on fellow EU states are all quite telling.
By contrast Britain almost seems like it dodged a bullet - although they seem to have jumped in front of a train instead with their pandemic gamble.