It's very good you were able to pick yourself up after the first year and do well in the subsequent years. What caused you to do poorly in the first year? This is the most crucial question that you should be prepared to answer to the visa officer. If the reason for your poor performance in the first year is not strong enough, the visa officer might wonder if the same reason could also cause you to do poorly in your master's program if you are issued a student visa to study in Germany.
So be prepared to give a very convincing explanation to the visa officer on why you did poorly in your first year and remove all doubts from his or her mind that it won't happen again. Wish you all the best.