Mixed Feeding Query

[MixedBerries]

Sorry for hassling everyone with multiple threads today! As you may know, our breastfeeding days are over but
I was just thinking....
I have about 9 days' worth of expressed breast milk in my freezer. When I switch over to formula, is it best to
a) feed him all the expressed milk in a 9 day block to delay the introduction of formula by 9 days OR
b) introduce formula right away and give him a dose of the expressed milk every day to prolong the benefits of having at least some bm?
I'm not sure what the relative benefits of each option are wrt fending off allergies and "virgin gut" etc. I hope that makes sense. I'm so tired.
Thank you again everybody for all your help.

I have absolutely no scientific evidence to back this up just my gut feeling:-

I'd give some each day to prolong the effects, as I'm not sure how much 19w ebf vs 21w ebf stacks up on the virgin gut theory.

9 days could last quite a while though (i'm guessing 9 x 8 feeds?) if you swapped a couple of ebm feeds for ff a day and worked down to none it would be easier than all ebm then all ff?

Have you wound down expressing, or are you able to hand express now the pump is going back so you don't end up too engorged?

TS, you're such a star. Thank you so much for your help.
I've decided to hire a pump and wind down slowly. So today have done expressing about every 5 hours. Will do this for a few days and go down to every 6 hours and so on. Will be hand expressing for the next couple of days unil the rental pump arrives. I have a single pump but tbh, find hand expressing easier.
So I will continue to have some fresh ebm for a couple of weeks I guess. Depends how my supply holds at a low expressing frequency. If I could just pump twice a day and maintain even a small supply then I will, but not sure if that's possible.

A friend of mine pumped twice a day from 6w until 9/11m (I can't be sure exactly) and made about half of her DC's needs. It does go against all they tell you but it worked for her (she wasn't bothered about how much she made or if her DC had formula so she was very unstressed by it all).

Hope that's helpfully to you?

That's good news. Was just looking at the Kellymom website and it explained that if a woman has boobs with a "high storage capacity", then infrequent feeding/expressing doesn't always affect supply. Seeing as I've had oversupply and can express over 300 mls in one sitting, it might just be possible (no idea why I've been blessed with this ability as I started with 34A boobs)! I do hope so. Two expressing sessions a day, I can live with. I suppose I just have to take it as it comes....!