How will we know when the little time of trouble has begun?

"?The commencement of that time of trouble,? here mentioned does not refer to the time when the plagues shall begin to be poured out, but to a short period just before they are poured out, while Christ is in the sanctuary. At that time, while the work of salvation is closing, trouble will be coming on the earth, and the nations will be angry, yet held in check so as not to prevent the work of the third angel. At that time the ?latter rain,? or refreshing from the presence of the Lord, will come, to give power to the loud voice of the third angel, and prepare the saints to stand in the period when the seven last plagues shall be poured out." . EW 85.3