For those who plan to or end up formula feeding...
My girls had gas issues, so using room temp water and adding powder and shaking the bottle to mix it up never worked for us.
In the early months, we kept a crockpot on the "warm" setting in our room at night, on top of the mini fridge I brought in from my office. I would pre-make the bottles for the night (we used a formula pitcher to make an entire day's feedings at once), store them in the fridge and then pop them in the warm water while I would unswaddle and change diapers. By the time that was done (a couple minutes) the bottle would be room temp and ready to feed.
By the time the nightime feedings were over, I just microwaved the bottles. I know, I know, but the danger in that is heating it too much and not swirling it to get hot spots out. 15 seconds and a few swirls and the bottles were the perfect temp. So much easier than running over warm water, using a bottle warmer (we had a couple and they would end up overheating and underheating), etc.
Hope that helps someone!
Re: warming bottles
We just stopped warming at like 10 months! Before that, they wouldn't drink it if it was too cold. High maintenance girls.
After 2 rounds of IVF & 2 rounds of FET, we were blessed with identical twin girls!
We would (still do!) just measure out the powder and have a nalgene bottle of room temp tap water, then fill the bottles when needed with water and shake.
H has reflux, so the bubbles from shaking did/do cause her to spit up more, but since it's only slightly more we just go the easier route of not needing to warm bottles. Though, now they are okay with cold ones:)