Preferably boil the coffee for 12-13 minutes. You could use a coffee maker instead, which shuts off automatically. However, it makes fairly weak coffee so you might have to run it through twice and use a little more coffee.
A very powerful method is to make enough for two enemas and do them back to back. Women can also do a vaginal coffee implant while they do a coffee enema, which is also very powerful.
To make the coffee cool quickly, use a small amount of water when boiling the coffee. After it is done, add more cold water to cool down the mixture.
While waiting for your coffee to boil, you could cut up your vegetables so they are ready for pressure-cooking, or you can put them in an electric steamer to cook them.