Maternity leave

Hi mummies, as im a ftm im not exactly sure how maternity leave. I only know im entitled to 16 weeks, however when do you usually start your maternity leave ? On the day youre admitted to hospital, on the day baby is born or a week or 2 before edd ? At which week did you give birth & start your maternity leave ? Or do i need to take AL a week before edd then when baby delivered thats when ML starts ? Since we also wont know when will baby comeout unless if its elective csect. I know some will say i need to ask HR but i would like to know mummies’ experience #FTM #pleasehelp