I asked because not all ratings in the Navy promote at the same frequency; advancing to E5 first time up as a Crypto Tech is impressive; not as impressive as advancing first time up as a Boatswain's Mate, or a Hospital Corpsman, but impressive, nonetheless (I was neither, in case you think I was throwing shade. I wasn't; I also served in one of those "quick advancement" ratings). That's actually half the reason why I got out of the Navy: I advanced to E6 very quickly, which is as high up as you can go on technical knowledge alone. To put on khakis, you have to be at least a little political, and I wasn't; the thought of spending thirteen years in the same paygrade did not appeal to me. But, yeah, propers to your nephew for putting on Second: Crypto Tech is a tough rate to get into. To be a CT, you not only have to score in, like, the ninety-seventh percentile on the ASVAB, you also have to be able to get a TS clearance, so it sounds like your nephew's got a lot going for him.
Also, I don't want to be that guy, but ESWS isn't a big deal anymore. It used to be, once upon a time, back when only the most highly motivated sailors would get surface warfare qualified, but it hasn't been that way in nearly two decades. In fact, getting ESWS qualified is one of the prerequisites for eligibility for advancement. If your nephew is stationed on a ship, and wasn't ESWS qualified, they wouldn't even have allowed him to take the exam.
Not that that takes anything away from his achievement. I still had to take the E5 exam twice before I made it, and I'm a pretty smart guy, if I do say so, myself.