How many toning sessions do I need to see results?

My skin tone is generally on the dull side, so I've been debating lately whether to get Pico Toning. I also have blemishes here and there, which are difficult to cover up with makeup. However, when I look at reviews, many people say that you won't see results after just one session, so I'm wondering how many sessions are typically needed to feel the effects. I'd also like to know when I start to feel like my skin has become clearer, and if the treatment is quite irritating!