Apparently they’re waiting for the right time to pull the trigger on social distancing measures. I genuinely don’t get it. They’ve seen what’s happening in Italy and they’ve got a few weeks head start. What exactly are they waiting for?
This will sound utterly heartless, but they'll have modelled the likely growth in infections and will have a time in mind when that hits a threshold.
That threshold will take into account the fact that any action taken won't effect those recently infected but not yet displaying symptoms, so there'll be a delay in the effectiveness of the actions. There'll be taking into account the number of people thought to be infected and run some sort of risk analysis working out how likely social distancing will have an effect.
Plainly there's a risk involved there that their modelling might be wrong, but there's also a risk that, if the general population aren't sufficiently concerned, then they'll replace one type of social contact with another, and the net result will be minimable
For example, see the number of people at Cheltenham today and Anfield tonight, and, if it goes ahead in front of a crowd, the number of people at Goodison come Monday. At the moment, despite the fears voiced in this thread, people are a bit wary, but not anywhere near as concerned as they possibly should be.
Once the numbers start to rise, and there are confirmed cases in most cities, towns and villages, then the public will be more open to taking instructions on social distancing.