Game releasing today, people already downloading it on steam but here its not available yet. How do we know timings? and why is it not aligned with the rest of platforms?

And why the hell are you posting this here?!

4 hours and 15 minutes left
you can simply check your library in browser and you can see the countdown

As GOG games aren't DRMed, they don't usually include preloads, you get the whole game when it is available.
Anyway, what does it have to do with Galaxy 2.0? Use the general discussion forum, please...