Help using colief

[pleasethanks]

I am about to start using this for my FF baby. I use instant formula and I understand that I have to warm the milk, add the drops, leave for 30 mins (with some shaking) and then feed the baby, ensuring the bottle is at the right temp. But, my concern is that it will be pretty cool after 30 mins but wouldn't it be a bit unsafe to effectively reheat the bottle after the 30 mins?

thanks

I've never used colief before, we used infacol. But what about leaving the bottle sitting in warm/hot water for the 30 minutes so that it doesn't cool down too much?