We don't have a definite answer to how long it will take you to get clear skin. The timeline is different for everyone, and it depends on how strong your belief is. The more aligned you are with the universal energy, the faster you can manifest clear skin.  If you keep thinking that it is challenging to manifest clear skin or how bad your skin is, you'll be hampering and slowing the manifestation process. You must strongly believe that your skin will get cleared up, and your manifestation will come true.