Duales Studium for international students

Hi everyone,

I I’m considering studying Duales Studium. However, my Highschool certificate from my home country isn‘t accepted in germany. Therefore, I am now studying the preparatory college. I will finish studying in July and most of the programs start in August or September. Can I apply now and then attach my certificate later? If anyone had the same experience, please share it!

And thank you.