How Far After the Big Bang Are We Talking About?

How far after the big bang are we talking about here? We honestly, at this point, we don't know because we haven't been able to push back that far. So it really depends on when you want to say this is a galaxy, and that wasn't as to when you actually say that galaxies started to form. And so I guess this leads on to a question of how do we know any of this? The good news from my perspective is that we don't, or at least we don't in all the detail,. otherwise I'd be kind of out of business at this point.