I'm not much older than you, OP, and started growing my natural hair (inc. a fair bit of grey) out last summer.
I still have a lot of naturally dark brown hair and my grey is mostly in a mallen streak near the front on one side, though I'm noticing more grey growing around it now. The dyed hair below the regrowth is slightly darker brown than my natural colour.
Ten months in, my regrowth is almost down to my ear now and the demarcation line has softened a lot. I found the first few months hard but now it looks more intentional and I'm more used to it. Early on, I'd use root spray or dark brown eye shadow (you can buy special powders, but eye shadow works as well) to disguise it, then I got fed up of doing that so stopped.
I think it's going to take at least another 18 months to fully grow out, but I actually have days where I quite like it now. I feel like I'm unapologetically embracing my true self, and it's so nice not to have to think about dyeing it every few weeks. I do get the odd pang of envy when I see someone with shiny brown hair, but I'm so glad I'm doing this now as it's only going to get harder the older and more grey I get. It's quite freeing. And much cheaper at the hairdresser's!
Keep going, it'll get easier!