I can't really quantify it as it was in drips but in general, since I already knew C and Python, learning Go was easy. I could have started to write a web app right away, following tutorials on Go website and elsewhere.

At the beginning it's frustratingly slow, as it always is when you learn something new, but if you know other C-like languages, picking up Go will be fast. You just have to put the time to learn standard library and Go way of doing some things.