It's not stupid. I had never heard of it before peanut and didn't know it was a thing and I breastfed my first two for a long time! Here is some info from the experts https://laleche.org.uk/antenatal-expression-of-colostrum/
Also don't stress if you can't express, I've never been able to and I'm 40 weeks today! I won't bother and just wait for baby to do the work! 😁
I needed to express some in the hospital as my baby wasn't doing a great job at feeding to start with. But I hadn't harvested any as the midwife told me not to bother. I kinda wish I had because she also needed extra feeds as my milk took a while to come in.