First time, first trimester

This is my first time pregnant and I'm on week 5 of my first trimester. I get it's still super early, but I'm super excited! I'm a list maker, a planner... So I want to get little things I can ready (and who doesn't like baby shopping?!) but my mother keeps telling me to wait because it's so soon, wait til the 3 month mark incase something happens. But 3 months?! I feel like I'm going to be behind! Did u guys wait until 3 months just in case? Advice please!