Gosh, it's been ages - maybe 3-6 months? It should also make your skin less dry in general. My problem in pinpointing it is that my bumps are always way worse in the winter, so any short term change can always be blamed on the weather. I really need to compare my skin at the same time of the year to get a good feel about how it's doing.
--AC, extra bumpy this am due to the first heating day of the year