when I was a classroom teacher on the Central West Coast of Florida, I gave a yearly emergency management lab on preparedness... my key emphasis was in fact to MAKE A PLAN...it involved many areas commonly identified, but with emphasis on when to put the plan into operation... that is to have a definite go-no go indicator...

there is an old adage in political science.. if you place a frog in a pot of cool water and gradually heat the water over a period of time, you can boil the frog as it will not notice the slight amount of day to day change... compare that to dropping a frog into a pan of boiling water where the frog immediately jumps out...it is hard to determine the degradation of the situation if the change is slow... have a definite, identifiable, situation or event that causes your immediate action

and for some situations a PACE model of alternative actions might be of use
P primary
A alternative
C contingency
E emergency