when I started supplementing I did 2/3 BM, 1/3 F. Then after a week or so I went to 1/2 BM, 1/2 F. Then I went to 1/3 BM, 2/3 F. He is now on all formula.
I think I waited about 10 days between each switch (I had to do a speedy switch because my BM supply was gone and I was using my freezer stash)
Personally, I didn't put the two in the same bottle (if that's what you mean). I first gave dd bm and then f. It was based on what I produced from pumping more than anything else.
Well, I wouldn't combine unless you are just trying to get LO used to the taste of formula. In that case, half and half is probably fine. That's what we did to get my LO used to it when my supply was first tanking and now she takes formula like a champ (wasn't given it until 4 mo and had been refusing it). Otherwise, I would give all breast milk and then formula separately. The reasoning is that once formula has been added, if the bottle isn't used within an hour then it has to be thrown out whereas the milk alone could be saved for later use.
Re: Breastmilk/formula ratio
when I started supplementing I did 2/3 BM, 1/3 F. Then after a week or so I went to 1/2 BM, 1/2 F. Then I went to 1/3 BM, 2/3 F. He is now on all formula.
I think I waited about 10 days between each switch (I had to do a speedy switch because my BM supply was gone and I was using my freezer stash)