"Write the vision and make it plain on tablets, that he may run who reads it. For the vision is yet for an APPOINTED TIME; but at the end it will speak, and it will not lie. Though it tarries (has not come), wait for it; because it will surely come, it will not tarry (stay away forever). Behold the proud, his soul is not upright in him; but the just shall live by his faith." (the understanding God has given) (Habakkuk 2:2,3)
When is the APPOINTED TIME? When the Lord knows we are ready to undertake what He has planned as He would! When we want no glory but rejoice in His righteousness and His way being made in the earth. He desires to "make our feet like deer's feet, to make us walk on our high hills." (Habakkuk 3:19)
We see there was a wide void between what God wanted for Judah and what they were willing to do. Correction had to come to them in the form of the Chaldeans: a bitter, hasty, terrible, dreadful and fierce people.
In Luke 17:5 the apostles asked Jesus for something, that He would "increase their (our) faith" after He had instructed them to forgive a brother who sins against them seven times in a day and seven times returns to repent. Sounds like a reasonable, in fact, excellent request. Jesus replies in v.7 "and which of you, having a servant plowing or tending sheep, will say to him when he has come in from the field, 'come at once and sit down to eat'? But will he not rather say to him, 'PREPARE something for my supper and GIRD YOURSELF and SERVE ME til I have eaten and drunk, and AFTERWARD you will eat and drink'?
One can imagine the strength, vitality and fitness of deer's feet. In that strength, vitality and fitness the deer scales the high hills before it. Likewise, we christians must prepare (study to show ourselves approved) gird ourselves (humble ourself will under His mighty hand and in His sight) and serve Him(rather than serving ourselves). His vision for all christians is that we be strong, vital and fit in Him; for Judah then and the church now. Then He can disperse us to our individual callings because we have proved to Him that we will do those things commanded us. He knows when our soul is upright in us.