you should minimize monthly payment because monthly payment = principal + interest. with minimal monthly payment your interest also min to a certain extend.

meanwhile save a sum of money externally and pay lump sum to the bank to knock off the principal to reduce the interest.

raising your monthly payment = more principal + more interest is not wise

I am using Public Bank,
My agent told me, I can only start paying the principle after lock period,
during lock period, can only pay interest...