Re: MF's comment / idea
Assume boiling water by the time you pour it will be 95C. Fridged water will be about 5C. Hence a 50/50 mix of the too will be to all intents half way between the two - physics, innit - ie about 50. So with a bit of experimentation, you should be able to get to about body temp, just like 'from the tap', by either using slightly cooled boiled water, or a slightly different mix.
So: I'd bet you that with a bit of checking, half a bottle of boiled water, mix in the milk powder in which time the temp will have dropped anyway (hence no bug issue in the introduced powder), mix in another half bottle of cooled boiled water, and you'll be pretty well sorted.
With mine, admittedly nearly 7 years ago, we used to sterilise bottles, fill with cooled (but not cold) boiled water and then leave them at room temp. Mix in the milk powder as req'd, quick nuke and then serve.
Doesn't boiled water have any effect on the proteins etc in the milk? Just asking, like?