If there has ever been a 'time' when the universe didn't exist meaning a time when there was nothing(ness) and that is something we don't know, just as we don't know if the universe has always been 'here'.
But in complete nothingness numbers exist. Mathematical forms are abstracts and abstracts don't need 'stuff' to exist. The immediate way of acknowledging an abstract is by appreciating beauty. Beauty can take on many forms.
Why something (whatever) should be beautiful we don't know, A hippo isn't beautiful to us but to a male hippo a female is an enticing creature.
In an imagined vacuum (a state or condition of emptiness/nothingness) mathematical forms exist. The most basic of these is a circle, then we have squares, oblongs, triangles and so on. All of these abstracts are built on numbers - it follows that the universe itself is created by the formation of numbers into patterns.
We call these patterns atoms/molecules/stuff, the universe has a background of numbers. And the universe exists by transferring the basic form from abstraction into movement.
The basic form is O. O is a form with an inside and an outside. Or if you like with a mind and with a body. That's all there is. It's that simple.
Everything in the universe follows this form, everything turns, dies, and starts again. This process has been given various names; from reincarnation to re-cycling - recycling is something nature does without our help - the way it has chosen is called the passing of time.
The universe also recycles, it dies and is reborn.
It just takes a little while.
The constantly promoted belief (induced by religions) that we are born to be good and obey (in order to enter heaven) is a tragic error in the concept of the universe's plan and an insult to mankind's intellect.
What does a frog in a pond know of the world's oceans??