I'm a color blind with a first class SODA. Its not a problem for me. I have mild red green deficiency. I can't see green to save my life. But like mentioned above, if you can see a traffic light, you will probably do fine. You already have a medical, so that's the first step done. Schedule the SODA test with your FSDO. Then do what I did. Go out to your local tower controlled airport and visit the tower. Tell them you are doing the test and basically, you want to practice. Get a two-way and ask a controller to shine two lights right next to each other for you. That was very helpful for me, it let me compare the appearance of the colors to each other. My difficulty was with the green light, it simply looks white by itself to me. But next to the white light, it has a blue tint that separated it. I took the test the next day and did fine. SODA's are good forever. Once and your done.