The authors of the msm-msm.com recommend working your way up
to the high dose for at least a couple of months and then you
can go back down to a maintenance level of 6,000 to 8,000 mgs
a day.
Ed McCabe in his book Flood Your Body, has a section where he
talks about MSM, and he said that the best results they've seen
are when you take over 8,000mgs a day for an extended period
of time (like 8 months).