Edit: I now see that Paul coined the "Don't be Evil" slogan[0]. I'm curious what his thoughts on its removal and what that portends for Google today. u/paul?
After 4 or 5 years of doing this you'll maybe know enough about how "everthing works" and what books says how to do what, or what company did what in what way, or the "state of the art", at that time you can start doing original contributions in order to not fall back.
Oh and also the Imposter Syndrome sometimes never really goes away :(
Not for everyone.
Get hired at any place where good engineering is done
"It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle
For me personally, 5 years was the point at which you start to gain confidence, but still don't realize how much you really don't know. I see that in a lot of people too. Getting my CS degree, I was told I knew a lot more than my peers (and apparently more than some of the grad students...), and did better than most, but it wasn't really until a decade into my career that I would say I really started to "get it." That is after reading dozens and dozens of books, many hundreds of research papers, meetups, conferences (and later watching/listening through whole playlists of conference talks). You are always going to be an impostor somewhere, because there are always things you don't know. The best thing you can do is stop pretending that you know more than you do.
1) Write a lot of code. Like a ton, more than anyone else on the team. 2) Get feedback from people on that code.
And that's how you start to beat Imposter Syndrome.