I am a 24 year old male with acne on my neck and chin and occasionally on my cheeks. I didnt develop acne until around 21 years old. I have been trying no diary for the past week and I am still having small break outs. How long does it take to see a differnece if dairy is my problem? Is there anything else I should be trying? I drink alot of water and workout 5 times a week. I also stopped drinking protein shakes to see if that helps.
Caffeine is also something you should consider cutting out. If you acne is hormonal, caffeine will only increase it.
Decrease your sugar intake too, this includes fruit. Try to eat mainly organic vegetables and lean meats (chicken, turkey etc.)
I struggle keeping up a healthy diet...I've managed to cut caffeine out, but I'm finding the dairy hard to stay away from.
It's great that you're looking to diet as a way to improve your acne. 
As for time, it really depends on you. Some people experience improvements in just a couple weeks but some people don't see changes until a few months down the road. Your body didn't get this way overnight, so it can take a while to reverse the cause.
Definitely avoid dairy and sugar. Check out my green smoothie thread. It gives ideas for incorporating greens (the #1 skin food) and other skin tips as well. Hang in there. The key is finding healthy alternatives to the foods you like. Once you start cooking healthy, enjoyable meals, it's easy to continue.
My advice would be to generally eat healthy and try cutting out one or two things at a time for a couple of months to see if they effect your skin. Almond milk is a good alternative to dairy. Try cutting out peanuts and peanut butter as well. It may also be that diet has no effect on your acne so try not to get too crazy with it.
^ Great advice Tim! I do believe diet has an effect on all things health related though--what we eat is so important, and diet trumps genetic tendencies. There are definitely other factors though like environmental toxins we are all exposed to. Detox is also vital. A far infrared sauna is one of the only ways to eliminate many of the toxins we get exposed to in our lovely toxic world of today. Haha Many gyms now have these set up for use--I definitely recommend people using one if they have access!
