It doesn’t necessarily mean that your labour will start sooner if you start harvesting colostrum early, but to be on the safe side it’s better to wait till 37 weeks!
I had a breastfeeding class last week ran by a midwife... it's now 36 weeks but the guidance was 37 weeks for ages so not everyone is aware it can be from 36 weeks now ☺️
Harvesting colostrum (basically any sort of massaging your breasts) increases oxytocin levels, which can lead to labour. That’s why it's recommended that you start to collect colostrum at 37 weeks, when your baby is full-term