You may find that a fixed mag scope works for you, however you may not.
Whilst you won't be swapping mag once shooting, it allows you to fine tune a scope to suit you. I hated the x10 Viper I tried for a while, however many people like them. Others will simply follow fashion.
I found that close targets were too blurred and also out past 40 yards was blurred. Some people like to use that to range. I just got fed up with shooting blurred targets. I ended up after lots of playing around using x8. I couldn't do that with a fixed mag scope.
I really would wait and look through some at the comp. If you are going to shoot the comp, just use what you have for now, it will do the job to get you going. Use a lowish mag and set the paralax at around 23-25 yards to start with and see how you go. Make sure that you know your aim points for different ranges via your mil dots and have fun.