I'll admit that it pains me to see me like this. And that's a good thing. Having a constant reminder of what you don't ever want to look like again is good motivation. For some, at the beginning of the journey it might just be a sad reminder of how much work needs to be done. In that case, take the picture and file it away somewhere. For others it serves as inspiration to change. In that case, print it out and post it somewhere where you'll see it. You don't necessarily need to frown like I did, I think that was just my mood at the time, but in some ways if you contrast a frowny before picture with a happy after picture, the transformation seems even more amazing.
Taking a "before" picture at the beginning of your journey is a very symbolic action. It means that you've acknowledged that you are on a journey and that you plan to make some major changes for the better. Because your before picture implies that there will be an after picture. And your goal is to take the after picture as soon as possible.
Depending on your goals, there might be a large gap in time between your before and after, and that's ok. The sooner you get started the sooner you'll get there. But it does help to see progress along the way. I took front, side and back pictures every two weeks. You don't need to have someone do it for you. Do it in the same place each time, put your camera on timer mode and you can take them yourself. After a month or two I was able to compare the initial pictures to the current ones and see some clear differences. Those inspired me as I made my way to my happily ever after photo (haha).
Which brings me to my next point. When is after? Are you ever really done? You think "Ok, when I lose this many pounds I have reached my target weight and have achieved my goal". I lost the 60 initial pounds and reached my "target" weight and found...that I still had a little way to go. I was pleased with my progress obviously, but there was still about 15 pounds of belly fat clinging on to my body for dear life. Who cares? Celebrate the fact that you made a goal and reached it. Take your after picture, be happy, and reward yourself. Sure, you still have things you want to work on...keep working on them, and revise your after picture from time to time. But if and when you reach that initial big milestone, close your eyes, take a deep breath, reflect on what you've accomplished and smile.