Hi Ikbal,
First of all, congratulations on your admission. My experience may be different from others, but from my point of view, visa officers tend to be more lenient with fully funded students (assuming you are or at least partially funded). I got my visa last May, and I showed only a 40–45 day mature FDR. Around the same time, I noticed in the Facebook group that two other students also received visas: one from BUET with a 15-day mature FDR and another with a 25-day FDR. Again, this should not be taken as a standard reference, I’m simply sharing these facts, as many applicants were rejected during the same period as well.
In my opinion, the source of income can play an important role, and you should definitely include a bank statement, whether or not it has regular transactions. So do not worry, open FDR as soon as possible, use your admission letter as a strong source of fund and FDR as backup. You have to do the best you can.
Good luck.
Best,
Asif