Most of these are excellent pieces of advice, and practices I generally try to adhere to. I don't use schema as much as I used to, but timbre is fantastic, clojure.test is great, and all of the core points are excellent. I've never had cause to use agents or STM, and atoms are best used when enclosing some stateful function.
In my experience the answer is yes but there isn't necessarily a hurry. I work in a small shop with 3 other Clojure developers who vary in experience from pretty green (I'd dabbled a bunch but have only been writing it professionally for about 4 months) to wizard (people who are going on two years and written the majority of the libraries we use, who are fluent in pretty much everything all the way up the stack). The learning curve for me has been like this:
Stage 1: Deep end. Given a task, I crack open an existing application and spend half a day to a day just trying to read it and figure it out. I struggle with my notions of state and immutability, make and test some changes until I think I have it figured. It's slow and arduous, at this point I'm reading Chas Emerick's book and mostly writing very standard clojure, dipping into and experimenting with things like multimethods and atoms.
Stage 2: Local maximum. I'm comfortable with some of the better patterns to pass around and manage state, make a lot of use anonymous functions, and a lot of my code looks like a let to establish useful local variables followed by a return. I get comfortable with writing programs either from the top down or bottom up, slowly building to a point where everything ties together. I start dipping my toes into core.async.
Stage 3: I get very comfortable with core.async and appreciate channels as a really nice way to separate concerns, you can build a whole bunch of neat little machines with channels. Sometimes I go a little overboard and roll something back to just using functions.
Stage 4: Start writing code where you realize you could use a macro. Macros feel about as hard as stage 1, with careful repl development and scrabbling to build some kind of conceptual framework where the whole thing hangs together. Transducers come out, I read about them and understand them conceptually, and get pretty excited about the use of pipelines, which present a much nicer way to chain channels together (where before you might use a map or write custom functions to do channel transformations, but they don't prove to be very composeable).
That's pretty much where I'm at right now. I'm comfortable, but there's still a lot of stuff I haven't really jumped into. One nice thing about most of these constructs is that if my conceptual grasp is wrong, things usually don't work at all, and that's a good time to ask questions to others.
As far as building a team? If progressing through those stages and having days that are frustrating followed by some big breakthroughs seems appealing, that's probably a good indicator that you'd fit into this sort of environment. When I was dabbling I made some progress and started to understand some of these mechanisms, but sometimes you need a problem staring you in the face that requires some fancy moves to solve to motivate you to push past what you know.
It seems daunting at first, but I sort of think that all of programming is. Practical knowledge can be acquired through experience, but it's expanding how you work theoretically that is the hardest and most rewarding.