Low timings are good - and those are quite low for DDR4
However, lower timing will make it more difficult to achieve high frequencies. If you want the frequency to go up (say, so the infinity fabric benefits as well), you may need to accept higher timings. Wendell recently uploaded a memory overclocking guide for Ryzen, you may want to have a look at that: https://level1techs.com/video/maximize-ryzen-overclock-ram-faster-fabric-speed
If you only care about RAM's own performance, then 2400 CL12 isn't bad at all.