It really depends how young you are and your skin cell turnover rate. If you're younger, the average cell turnover rate for skin is 28 days, which means that it takes about 28 days for new skin cells made at the bottom to make its way to the top. If you're older, your skin cell turnover rate slows down dramatically--up to 60 days! If you're in between--well then estimate. I always say that most people should wait about a month to see slight results, and 8-12 weeks to see [likely] full results. Naturally, depending on the product and its strength, many times people can see a difference almost immediately or within a week.

Therefore, wait a month to see if there's any slight change, but wait 2-3 months to see bigger results. 

DITTO to Volta...I would only add that if you purchased this from QVC, make sure you use the maximum amount (once a day, twice a day) and keep using it until you hit 29 days (if you do not have irritation).  If, at his point you have seen no improvement, you can send it back for your refund.  It is difficult to get a REAL feel for a product without using it for 60 days, but this is what I do with my QVC beauty products.

How did I know QVC, it is the only place with Dr. Perricone's Vitamin C Ester right now.  Please let us all know how it works out for you!

Yes, about a month.  Hard to wait, I know.  But you have to give it a chance.  Like any new relationship, you hope for the best early so you don't waste any precious time.  BUT, taking it slow works wonders!

Good luck!

I AM VERY IMPATIENT WITH NEW PRODUCTS. BUT YOU HAVE TO GIVE THEM A CHANCE.

OF COURSE IT ALWAYS DEPENDS ON YOUR SKIN.

I too am really impatient! I like to be able to at least feel results within a week. I give it about 4-6 weeks to see results. The problem is that we look at ourselves everyday so it can be hard to see changes. We forget what we looked like at the beginning. Try taking a picture of yourself to begin with and then compare 6 weeks later! 

i agree with taking a picture.  it's the best way to see for yourself if it's really working, or not.  i've done it for myself and the change is far more noticable that way.  you can even use a magnifier when taking the shot.  that way you can see results faster than if with the naked eye alone.  the best thing, though, is to know your skin.  i.e. if your skin is oily then it will take a little longer to see results for fine lines than it would be if it were dry.