I think better wait till u deliver first. For all u know u'd be blessed with ample supply. Even if u don't, u can request from the hospital. Monitor to see if baby is OK with tt FM. Hospital will charge u and u can bring home the leftover. Unless baby seems to be allergic to it e.g developing rashes or keep vomiting, then u find another brand FM.
I bought while otw back home from discharge. Hospital gave me a few choices so I chose Nan, baby drank and had no issues then I stick to that. You can try out in hospital first, if baby ok then ask your hub to buy online or go NTUC buy.
I bought Nan in advance. Hospital gave S26 and baby took it well so I ordered online before I was discharged.