Congratulations! Those with warranty and expiry dates can wait till last trimester/2 weeks before EDD. Eg sterilizer, breast pumps, detergents, wet wipes etc etc. Clothings/strollers/car seats/cots and carriers etc can browse first, go down to mummy market/baby fairs to try out and see the actual product then camp for sales. I find usually shopee/lazada with stack on vouchers sometimes cheaper than baby fairs. To save further more, can request hand me downs clothings from your friends or Carousell as they outgrow quite fast :).
best time is after finding out baby gender