Hi KCLau, how do i calculate if i benefit from paying off my houseloan early?

i have a semi flexi loan with public bank. currently my property is still under construction and i have been paying interest on the amount that the bank had disbursed to the developer so far. as this is a flexi loan i can choose to pay off some of the principal; this means i will not have to pay that much interest. How do i determine if I should pay off some of the principal now (without paying fully of course because lockdown period is 3 yrs from 1st bank drawdown), or should i start paying only when the property is completed?