The eternal covenant

Before the beginning, the true eternal and infinite Trinitarian God entered into an eternal mutual agreement or covenant - the Father with the Son and both with the Spirit. In this covenant, certain ones yet to be created were considered to belong to the Son and so set apart to him. At that time the detail of how this would be brought about was agreed. Whether these chosen ones were seen as sinners or not is unclear. The essential thing about this covenant is that it was a covenant of grace not works.

Before the beginning

Before anything else at all, there was only the immense, infinite and eternal God. There was always God who is spirit and has no body. There was no-one else and nothing else.
God has no beginning. He is in every place and fills every place. There is nowhere where he is not. 

This God, though simple in his make up, was never lonely or self-centred for he was always one and yet three. He existed in perfect happiness and harmony always. He was always what we usually refer to as Father, Son and Holy Spirit - three equal persons yet one God with an order wherein the eternally begotten Son, though equal to the Father in every way, willingly submitted to him and the Spirit, again not inferior to the other two, proceeded both from the Father and from the Son.

Even at this point he knew all things, including exactly what he could or would do and the consequences of his every act.