Whenever the fuck you feel like it. Just know that DT spikes in difficulty a bit above 5*, HR on tv-sizes is for bitches, HR'ing stuff below 4.5* will only really teach you how to acc and mostly only acc'ing singles and triples at that, and HR'ing anything below od7 is pretty pointless.
Oh, and hidden is only worth learning if you care about having your name on scoreboards. It's much easier to acc/aim without it so it's somewhat detrimental to pp farming. The amount of time it takes to pick up is better spent learning how to play harder maps if pp is all you care about.
I'm slow like a turtle. Plz no bully, I hide in my rock hard shell.
Acctilt on DT/HR is too strong. It takes a few ms worth of nervousness and fatigue to net you a pattern full of 100s or a few misses so it's hard to know whether you really can 99+% or bad acc FC a particular map you claim you can do until you retry it a lot.
Whenever you want, I play for two years and haven't learned hr yet because I don't like it. If you start really soon you can always progress later, just don't stop playing what you already know how to play.