God is often used to explain the unexplainable. When man first came on to the scene and he coudnt figure out why something was going on he created a god to explain it. When too many gods were created it was found to be simpler to have just one god to explain it all.
Time by definition is finite. The beginning of time is directly linked to the beginning of space. There was no "before" the beginning, because "before" is a temporal relationship. God always "is," in traditional Christianity. The question, "What was God doing?" doesn't make sense if God is eternal. The question should always be "What is God doing?" The answer to that question is that God is creating and that God is loving. This is done with no beginning and no end. It (not-quite-so)-simply always is.
My understanding is he created the tennis game and got tired of running from one end of the court to the other trying to score against himself. So then he created a few angels so he could find someone he could beat in the game. He got bored with that so he created the earth to see how other creatures would fare at the game.
Our finite minds find it hard to comprehend that before the universe was created, God existed alone. So, before time even existed, God existed in three Persons: Father, Son and Holy Spirit. The Trinity existed in perfect harmony and flawlessness, having all they needed in one another. So before He created the universe, God experienced absolute satisfaction in Himself. God dwelt joyfully alone in eternity as the Trinity. These three were together in fellowship with one another from all eternity. They loved each other. We know at some point they discussed the redemption of mankind (Ephesians 1:4-5; 2 Timothy 1:9; John 17:24), but everything else lies in mystery. http://www.gotquestions.org/God-doing.html
Time is a relative reality specific to the universe...therefore there it isn't infinite. God however is infinite in a state of eternal being (an ever-present "is"). No offense, however the phrase "was doing" is therefore irrelevant to God's Being prior to the universe...there is no actual past tense from the "perspective" of God. Not sure if that is the answer you were looking for...feel free to comment. :)
Our finite minds find it hard to comprehend that before the universe was created, God existed alone. We know from John 1:1 that Jesus also existed: “In the beginning was the Word and the Word was with God, and the Word was God. The preincarnate Christ was intimately united with the Father, so as to partake of His glory and to be appropriately called God. He has Himself explained it in John 17:5: “And now Father, glorify Me with Yourself with the glory which I had with You before the world was.” We also know that the Holy Spirit was present before we were created. Genesis 1:1 describes the Spirit “hovering over the face” of the dark and formless earth. So, before time even existed, God existed in three Persons: Father, Son and Holy Spirit. The Trinity existed in perfect harmony and flawlessness, having all they needed in one another. David said in Psalms 16:11 that "joy and pleasures forever more" are in the presence of God. (My answer continues in the comments)
We dont know that obviously but other heavenly beings are there, those we call 'angels' so i assume He kept busy with them. And how do we know there isnt another 'earth' in another place, maybe several. Not saying there are but you never know. Maybe there is a world with beings in a universe outside ours that we cant even imagine!
In fact this eternal god of bible, since man created him, only worked for SIX DAYS in his whole life while supposedly creating this universe - so says bible. Supposing that this same god existed (which is an infinite impossibility) he did just the same as he does today (& no doubt that he does it best) - he sat in utter LEISURE & absolute IDLENESS.
There can be no logic answer to this question, whatever the answer maybe. But as everyone tries to give their shot, here's mine : If there was god anytime, firstly he would have made the time to be infite, since its the most important parameter to begin with the making of universe.