I didn't see it in the patch notes, so I am guessing after August (the last entry in the patch notes.)
You know that the formula for 100% is not that complicated right? For SR, if it is at X slvl, you just need X R weapons. For R it's half X, SSR is 2X. If you are using grails and SR weapons as fodder, you need to remember the multipliers, but it's really not hard once you've done it a few times.
Usually people complain about wasted fodder when going over 100%, so I can't just stick 20 R weapons on an SSR and expect it to go straight from slvl 1 to 5. The new system would solve that. If you play the daily 15x10 gem gacha, you should have lots of R weapons such that there is little reason to ever be under 100%.