How long should I wait to turn on the water in my kitchen, after Ive soldered the copper pipes?
A soon as you can turn the tap on.
Solder joints can be used as soon as the solder cools below melting point. Basically as soon as you are finished. I try to give a couple minutes to avoid thermal shock.
You don't have to wait at all. Cool it down with a wet rag when done. That will also wipe the flux off as well.
