Though I started in 2008, I didn't really make any attempts at monetizing until late 2009 and started with Adsense, then linked all the albums reviewed to two online stores that sell the CDs in question. All told, it took me maybe 3 months to make my first dollar and even longer for affiliate commissions to come in. I didn't make my first sale until maybe February 2010.
Obviously this isn't a product-based project, so it's not representative of the webapp stuff that others are producing.