Hey, I have a similar problem, I

sunburned badly and now I'm paying for it. I have been using pure aloe vera three times a day to avoid peeling. I did this last time and it worked. I think it's a little late for you, but you can start using it. Just keep it moistured at all times and see if it helps. I'm just a health frick (believe it or not!) and I am sorry I did such a stupid thing. I am taking vitamin C and E that together work effectively to help skin recover (actually vitamin C just helps absorption of E), and I'm also drinking lots of water and green tea that supposedly heals the skin if applied directly, but I'm doing it from the inside out (just my theory).
So far the pure aloe seems to be working fine. This happened on Sunday. I subscribed to this chat room because my sunburns were patchy, so I'm going to look (actually look) like a dalmatian. It was so bad in the back of my legs (close to the ankle) that it looks like a bad rash and hurts when I'm standing and not moving for a short time. Today, Wednesday, the pain is almost gone, but I have been using all sorts of creams besides the aloe and alternating, even vitamin E applied directly.
Anyways, I was hoping to find someone to tell me how to get an even color back again, but then I think it's just a matter of waiting for the color to go away. I hope someone could help us if there's a quick fix.
I think that you still have time to recover an even color by July 8 and on that date you will probably be much better and if you use a sunless tanning lotion you might be able to hide it better.
Well. I hope this was helpful, and let's be more careful next time.