I seemed to hit my limit at about month 6..7.
I can't be sure but there were a second bunch of new small hairs at about month 5, they grew a bit and then stopped and have not grown anymore in 4 months. They are cosmetically insignificant. My hair is as good as it was at month 6, but no better. Most studies show that after a year is usually when it peaks for most, although in long term follow up studies a certain lucky few had greater density at year 3 then year 1. (Google minoxidil follow up study).
>Hair regrowth with topical minoxidil peaked at approximately 1 year of treatment with a slight but not statistically significant decrease in 1-year counts seen at the 3-year visit. At 1 year there was a mean increase in nonvellus hairs compared with the baseline count of 273.4 and that at 3 years, 246.2.
...
>However, some patients receiving long-term treatment with topical minoxidil continued to have an increase in nonvellus target area counts at 4 1/2 to 5 years beyond their 1-year counts (n=9). Similarly, a few subjects, despite continued treatment with topical minoxidil, had nonvellus target area hair counts decrease below baseline (n=4).
http://www.anagen.net/m14.htm