How to freeze my refrigerated milk - advice??

I used to keep all my milk in the top part of the fridge as my baby was drinking it within a few days, but the stash in my fridge is getting older now because I’m pumping more than baby is drinking.

I have milk dated back from August 31st and I’m wondering how far back can I put milk in the freezer once it’s already been refrigerated? I don’t want to waste any milk and 5 days is about as old as I’m willing to let it go.

What date milk should I start putting in to freeze? And should I do so many bags from each day?