You'll get the most regrowth in the first 4 months (usually), then slowly improve more over two years. After 2 years you won't improve anymore, you'll maintain or slowly decline from there. Some people report a faster decline at anywhere between the 6 and 10 year mark where the drug may appear to no longer be working. Not sure how common an issue this is. At this point you may need to switch to dutasteride to buy some more time, or possibly some experimental treatments. Hopefully there will be a new technology by the time dutasteride also loses it's efficiacy if this happens.