I would have thought that rather than providing dates for things it should be related to factors like level of vaccine distribution, R value, level of hospitalisation etc etc whatever metric they felt was best. They can then always say "at the current rate we would be looking at the first half of March", that gives plenty of leeway. At this stage I don't think anyone would be annoyed at timescales with a fair bit of uncertainty built in but would be pretty ****** off if there are set dates that are either pushed back if things don't improve as quickly as expected, or are followed regardless of circumstance and lead to things spiking again.