I started expressing at around 2 weeks - MW suggested we give it a go, as DS had good latch, strong suck, was generally doing well (this is only relevant cos she said babies who aren't well established BF-ing can get 'nipple confusion' if you introduce a bottle).
Her advice was just to express a little at the start/end of each feed, and not to go mad in a single pumping session, as my supply might go into overdrive.
My DS is currently 4 weeks, and my DP usually does 2 feeds at night, across about 5 hours. It is SO helpful in letting me get more than 2 hours sleep, it really has made the exhaustion of BF-ing more bearable.
(I'm no expert, btw, this is just my experience and what is working for me atm).
- I express mainly in the morning, and not really at all in the evening, as I have less milk then. I express a bit at the start of a feed, and some at the end, and mix it. This is cos the early milk is thinner and more watery - the later milk yellowy and more creamy looking. I feel like that 'mimics' a full boob feed, IYSWIM.
- My DS takes between 70-150 mls over a couple of bottle feeds, across 5 hours max (growth spurts aside!). It depends how big his last feed before that was. I tend to get 50-70 mls from pumping either side of a feed, so it's pretty easy for me to build up this amount each day. Offering several smaller amounts rather than one big bottle means if there's any left over in the fridge, it can be frozen.
- Warm it up in a jug of warm water. DS refused to touch (accidentally offered) cold milk!
- I just used medela bottles and a slow flow teat as that was what I had. DS was fine with that, I haven't experimented further.
When we tried it, my thoughts were - whatever I express, if DS gets through it and is still hungry, then DP can wake me and I'll feed him. If I've had more than 5 hours 'off duty' feeding-wise, and DS still has some left in the bottle - DP will wake me up. I find going more than 5 hours without feeding leaves me with uncomfortably full breasts, and apparently going that long without feeding at night can affect supply. (my supply has been fine so far).
Long post, sorry. I'd also recommend Colief, if you haven't already tried it, and your baby is small and colicky. Good luck!