Was there any preparation for the first coming of Christ taking place in the spiritual world during OT time?

Does the Bible contain a thought or any indication of it that throughout the whole Old Testament era there was a process of preparation for the first coming of Christ taking place in the spiritual world? We know that in the physical world there was a process of preparation taking place for the first coming of Christ – in the way of God’s firstly forming a chosen nation, then revealing to them some standards of His righteousness, and later, through multiple periods of their history, showing to them that they were unable to live according to those standards by themselves, that they needed to fully rely on God’s saving hand in the matter of their salvation – despite possessing the status of the chosen nation. But what about the spiritual world? Does the Bible contain any indication that there was also a kind of preparation for the first coming of Christ happening in the spiritual world during those times (perhaps, some kind of spiritual warfare happening between God’s angels and fallen angels, the outcome of which made the first coming of Christ possible)?