I read about B12 deficiency and how bad it can be and I want to prevent that.
What What B12 supplement you using and where did you get it ?
I advise you to do some blood test to check if you're deficient or not. I am. I did my blood tests 2 years ago and I was. I did them again 2 weeks ago and still am.
However, keep in mind that NOT ONLY VEGANS are deficient in B12 ! (I think there are sources online but sorry I don't have any links right now). Personally I can't help you with supplements because I'm not taking them, I think someone who has experience with this can be more of a help !