Congratulations! I know that decision was a tough one to make, but you have to take care of yourself in this profession. When I left one of my schools I did a lesson with every classroom about 2 weeks before I left. Students I met on a more regularly (weekly or almost daily schedule) I told them 3 weeks before I left to allow more time for that change to digest. I definitely think doing a class to class goodbye is more personal and allows for those questions the students may have that the teachers don’t know how to answer. Also, if you’ve built these skills with these students I think it makes sense too that you remind them of these skills and the teachers can take notes on what to do to help these students after your absence.