I found it still helps even after you screw up your hearing. The ringing never goes away but if you wear hearing protection for every loud noise around you after a few weeks/months the ringing gets better--softer. That means your hot rod car also if the exhaust is loud. Lawn mowers, leaf blowers, drill motors, etc. Always wear ear muffs/ear plugs--or even both. The longer you can go without hearing loud sounds the better the ringing gets.
Least that how it is for me. If I go without ear muffs and my ears ring loudly, it takes days for it to die down. Never ever goes 100% away but it can get very soft that you won't noticed it all the time.