How long does it take to remove acne scars with lemon juice? It depends. I can't tell you for certain. It could be as little as a couple of days, and it might take a few months. It's probably somewhere between those two figures. It depends on a lot of different things - your skin type for example. If you only apply the lemon juice every now and again, then that will have an impact as well. You can deal with the second one - just be consistent with your treatments. The first one (your skin type) will have a bigger impact then you otherwise might want it to have.
But, what I do know is that lemon juice is a great natural acne scar reducer. I'd say try and start today if you can. Lemons are cheap, and you may even have a tree. Simply squeeze out the juice of a couple of lemons, dilute slightly with water and apply with a couple of fingers. Yes, it stings. Lemons are very acidic and so you must be careful with them. Garlic and tomatoes are the only other natural treatments I strongly urge you to perform a spot test with - it's so important!
As I mentioned above, consistency will be the key to getting fast results with lemon juice. Try and perform the treatment once a day, or every other day. I'd do it in the evening - this is because for reasons unknown the skin reacts much stronger to sunlight when you've just applied lemon juice - so please don't go out in the sun after putting lemons on your skin, because you'll get burnt faster! And burning the skin - especially skin that's been scarred - is especially bad. They're very natural, so lemons are a great way of bleaching the skin and helping to reduce the appearance of your acne scars.
source: http://www.streetarticles.com/acne/how-long-does-it-take-to-remove-acne-scars-with-lemon-juice