There is the question of what God did prior to creating the universe, but there is also the question of what God did during the first more than 13,000,000,000 years of the universe’s existence before humans arrived on this planet.
Most likely He occupied himself with other civilizations on other planets around other stars and galaxies. Humans are probably just one of billions of communities created by God.
Interesting idea. But if God created lots of different worlds why did He go to so much trouble with ours? He sent his own son to die for us so we could be saved even after we screwed up time and time again. And He knows we will keep on sinning. Are the creatures inhabiting the other worlds just as bad? And if so why can`t God improve them (or us for that matter)? Or does He not want to?