What's the best method upon filling a hot water bottle?

I moved to reply number 10 and decided not to read more.

I use a sauce pan to heat up the water, this allows me to see the correct amount of water to use, then after heating the water, pour into the water bottle, then, and this is very important, I flatten the top part of the water bottle to release the air and then screw in the cap.
Finally I shake over the sink to check for leaks before wiping any spillage of water between the cap and the flared top.

Are NSC members using their hot water bottles already?

I still have my summer duvet (3.5 tog) on my bed.