Can you mix breastmilk?

My doctor recommended that I pump my colostrum while I’m still pregnant to save for my baby once he’s born. But when I do, I’m only getting around 2 ounces for both sides.

Once my son is here and I give him his first bottle (probably not until week 6) can I mix different days of colostrum together? Like say I have one bag from 9/26 and one from 9/27?