From the front line... Went back to work full timewhen DS1 was 28 weeks old... He's now 34 weeks. He started on solids (because he was grabbing at food) at about 20/21 weeks. In the last few weeks before I was going back to work I went from daytime milk at 9, 11, 2, 5 to 11 and 2, and sometimes 5. I also expressed a little (15 portions perhaps?)and put some in the freezer. Baby is at home with Dad (who is on shared statutory parental leave). I'm out 8 - 5.30 ish usually. Baby has had something from a bottle most weeks of his life, we got off to a very iffy bfeeding start which included lots of formula in hospital and in the first 3 weeks of his life, and I expressed and bottle fed some times whilst dealing with various boob issues up til 12 wks or so. So basically he's been used to bottles.
In the very first few days, I would offer him a feed when I came home from work about 5.30, as he was still on and off having food in the evening. Since Christmas, my routine is: morning feed on waking, express from the other side during breakfast, go to work, express as soon as I get home, evening feed at 7, night time feeds as and when (that's a whole other story). So I express twice a day, which provides DS1 with two bottles a day, which he rarely finishes. Usually I get about 150 ml in the evening, more like 100 ml in the morning.
I was terrified about leaking at work, but I haven't (though I have spare top at work just in case). I could express at work, but I don't want to; I want to leave mum stuff behind and get through the day. Apart from the first couple of days, (I'd never left him more than 2 hrs in the daytime at that point) I've not felt I was going to burst, I took some milk bags with me thinking that if I did feel full, I could hand express, but I haven't apart from day 1.
I thought by now I'd be using up freezer supplies, but I've barely touched them. Aso, for those babies with dairy issues, so did my little one, but since 7 months he is fine (which is great, 5 months without milk or ice cream or milk chocolate or any of the random stuff with dairy in is quite enough!), but I had the same formula worries on going back to work.