Hello student. You can either get the signature from your old school principal or from centre supervisor. But, it is always better and safe to get signature from your old school principal. Go to your old school and contact your principal and get the signature so that you won't gpface any sort of any glitches during your exam about signature. If your old school principal himself suggests you to get it from centre supervisor, them go for it. But meet principal first.

All the best for your exams

Regards

Nikhitha