I thought that you are supposed to keep milk separate from different times of day since it changes over the course of the day - so you would have morning, afternoon and evening milk labelled? I don't know why I think that this is the case, maybe i read it somewhere?
I read this too but found it way too complicated, I was just happy that L's caregivers were willing to deal with defrosting breastmilk and storing it correctly, nevermind worrying about when I pumped it.
I think that research about the levels of things in the milk is really neat but I question whether there is a huge effect on baby's behaviour in contrast to the signals they get about sleeping and waking from the light outside and their body rhythms. Once they have their days and nights straight I think it would be hard to mess with via occasional pumped milk.
I used several storage systems but ended up preferring the milk storage trays
that freeze milk into 1 ounce sticks. Really compact storage, really easy to use, and less wasted milk. Once a tray is full you just pop them out into a good freezer bag and date the bag, I would keep 2 weeks worth of milk in at a time and then get a new bag, and I would transfer it to my mom's or MIL's by using the medela insulated cooler with their
L never needed more than 3-4 ounces at a time when he was under 6 months old (he reverse-cycled so he would nurse all evening/night) so I would also freeze my milk in 2 and 4 ounce sizes when I was using the playtex drop-ins, those are the next most affordable, and again I would just freeze the bags with the caps on and then transfer to a freezer bag so I didn't need as many sets.
Once breastmilk is frozen, if it's thawed it needs to be used that day, so until you know for sure how much milk your LO takes in at each feeding it's best to freeze in smaller quantities, otherwise you end up choosing between throwing the leftover milk away and pumping at home (you're supposed to throw the milk away and nurse your baby because nursing is better at keeping your supply up than pumping, so sad to throw away milk though!). The book "nursing mother, working mother" has some great information in it. Ideally you can pump milk and send that milk with the baby, because whatever doesn't get consumed can be frozen, and the caregiver doesn't have to worry about defrosting anything. I would take my pumped milk from the day before and send that, and use the freezer stash for when I hadn't been away the day prior so had nothing fresh.
I started pumping about a month postpartum before my supply had regulated, I think it helped ensure I had enough pumped milk for him in the first few months. My pumping mistake was that I didn't pump long enough once I was away from L all day, my supply gradually dwindled because I only pumped once a day.