Right now it seems to take about 25/30 mins. We boil the kettle, sterilise the bottles, wait for about 15 mins for boiling water to cool down slightly, then after making up the bottle we pop it in a jug of water to cool down to "wrist temperature".
This means we occasionally get the timing wrong and its all a bit fraught! He's on a three hour schedule but at least once a day there'll be a period where after 2.5 hrs he's decided he wants his feed NOW but there's no kettle even boiled!
We're trying to go by guidelines but I can't help thinking we're missing a time-saving trick?
(BTW I know about the TT Perfect Prep machine but DH is dubious about it)