I had a pretty terrible experience at that job - no engineering manager, never had any code reviewed, hardly any collaboration with other team members so I was basically stabbing away in the dark trying to get my shit together in TS.

It took me far longer than a few hours to feel comfortable, probably more like over a month of coding to get to the point where I mostly understood how to express what I wanted with the type system, and had stopped doing C# things in TS and adhering to style guidelines - functional modules, types instead of classes, injecting dependencies etc. And another month or two? to really figure out how everyone has been (ab)using the type system to do more complex stuff.