35 years
You started in 1976 or earlier?
~10 months
I practiced a lot of big cubes and I had a sub-7 7x7 avg. before I was sub-minute on 3x3. It took me about 1:30 to solve 3x3 stage on the 7x7 back then.
What do you average now on 5x5 6x6 and 7x7?