It is thought that no one can know the time and they leave it at that. Here we see that the indications will be discern-able just as a shift in the weather.
That this teaching about settling up with ones adversaries before going to the judge is so close to the earlier talk of being watchful and prepared for the Lord's return indicates the urgency and type of preparations to be made.
I think that it is too easy for us here to judge Peter. He is not reborn yet. He is still trying to approach his relationship to the Savior Christ in intellectual rather than spiritual terms much like us. The fact is that none of us truly know how we would have reacted ourselves faced with this hostile and surreal situation. Rationally, if denial meant being able to continue observing the nights events without having been set out and/or beaten it may have been well worth it in a more practical way. None of the other twelve after all were risking the effort to witness the events unfolding; only the two Marys and doubting half brother James were also watching on.