It's been 3 years since my hair first started to turn grey due to AF, congested liver and copper overload alongside biounavailable copper.

If the grey hairs are reversed with bioavailable copper or paba and tyrosine, would it take the same amount of time to turn all or most of the greys back to their original color or is that not how it works?

I know you told me it takes several months (6+) for the newly pigmented hair to grow from the root but would the pigmenting process be as slow as the greying process? On average I've been getting 20 white hairs per year so have 60+ now.

Repigmentation is generally pretty quick once the source of the problem is addressed.  As the base of the hair pigments it will gradually grow out with the color.