You're okay doing it one time. Even a couple of times. Just don't make a habit of it and you'll be fine. Try to drink diet sodas so that you can prevent cavities. Drinking with a straw also helps a little also (keeps the soda from pooling in the biting surface's pits). Chew sugar free gum after drinking soda and it will help neutralize the acid and will also kill the kind of bacteria that cause cavities. If you don't want to chew sugar free gum just rinse with water after drinking the soda. Glad you care about these things, you're on the road to having great teeth for a lifetime. Keep up the good work.
No need to worry, soda is not strong enough to decalcify enamel .