‘Self awareness’ is how we call our ability to observe ourselves while observing others.
Humberto Maturana
First and foremost, existence is a concept.
Something our forefathers had coined. A mental construct built by talking about it.
Nothing existed before we saw it AND talked about it!
Think about the stars nobody knew about until we used Hubble to peek into the history of the Universe.

Think about the stars which ‘sit’ there and no man will ever see. Or otherwise perceive.
Think!
Do they, the stars, actually exist?
In the sense that has their being been ‘measured’ into existence by a self aware observer?
Has that observation been communicated by the observer to anybody else? Who had confirmed that that observation was anything more than a mere illusion?
You see, both actually – my rantings on your monitor – and figuratively, I don’t need to be told about the existence of the steps I have to climb up and down when I leave my bed each morning. On the other hand, I know that the Amazon exists because I’ve been told about it. Further more, I see for my self the steps in my house but I have a name for them – and I can write about them – because our forefathers had learned to speak. About the world they were discovering around themselves.
My point? We speak things into existence, not into being.
‘How about the things we talk about before we’ve ‘seen’ them? Neptune, the planet, had been ‘calculated’ before ‘seen’ and all mass manufactured things are first discussed and only then launched into production.
Which was the exact moment when each of them had started to exist?’
Good question!
I’m afraid I have no valid answer. This is a matter which will remain open for further debate!
After all, how else to justify our existence?
How else to find our own meaning? Other than by talking about it?