Well from religion perspective , here is what rig veda says
Some other place it also says that before the ultimate creation even time didnt exist so no point pondering how long things didnt exist.
basically the common belief is the 3 levels (Lok) of creation get created and destroyed, and again created and destroyed over and over again. like big bang when things got created and at one point it will shrink to its original form and everything will cease to exist and then big bang will happen again and same cycle will keep on repeating.
to make myself clear i dont try to find scientific answers in religious texts.