I put 21 to 30, but now I find I misread the subject. I thought it was save not earn, and I went from when we started saving not started working.
So it was 39 years, I started my first job in 1969 at 14, from there it took 39 years (2008) to earn 1M with both my wife's and my income. Didn't start saving until I was 26.
I don't have an exact number, but we probably had over $700k saved by the time we earned the 1M.
Closest NW statement I have is the end of 2010 and that's $936K, That didn't include our paid for home.
SS is a bit misleading because we had some real estate profits that weren't SS taxed.