holy shit that's crazy. I roll it off too, but I'm only 225.
How long does it to get gains at your level?
It took me about 5 years to bench 315, then another 6 or 7 to bench 350, and probably another 5 to hit 370.
I'm a very slow gainer and sometimes focus on martial arts or boxing over powerlifting, so my progress is probably not typical. At least I have consistency.
Currently playing: Skyrim, Hearthstone
Training log: https://powpowpunishment.blogspot.com