That’s not for everybody.
It will help you a lot to learn, but IF it is not balance, it could block your learning process.
It depends on your UNIQUE way to perceive the environment, the context, your feelings and the message you want to share. Sometimes the message is more important than the language, even if you are in English class.
So, is it ok to use my first language during the class?
It will be better if you speak English BUT if you feel an urge to say something and you CAN’T say it in English, use your native language and the Teacher or a classmate could show you how to say that important message:
We built knowledge together, it is not only on the teacher’s hands. As it is really important for you, you won’t forget it.
The learning process goes beyond demanding the use of L2 language: it is EVERYTHING that occurs inside the student when is in the classroom: anxiety, frustration, excitement, etc.
Rule number 1 to learn English: Enjoy it! that way your brain will retain more information for longer periods of time.