If the needle on your Keurig machine becomes clogged you can use the tool that comes with the Keurig to unclog the needle on the Keurig.
If you don't have the tool to clean the needle on the Keurig machine then you can use a paper clip that you unbend to insert into the Keurig needle.
After cleaning the needle on the Keurig and removing any buildup you should also run some vinegar and water through the Keurig machine which helps remove hard water deposits and calcium buildup in the Keurig machine.
If your Keurig is not fully clogged and you just want to clean the Keurig coffee machine with the vinegar then there's no need to let the vinegar sit for any amount of time in the Keurig.
After adding the vinegar and water you can immediately start the Keurig machine and allow it to go through a brewing cycle to clean the Keurig machine.
If the Keurig is clogged and not working properly then I would recommend adding some straight vinegar without water and allowing it to sit for 10 to 20 minutes.
Then run the Keurig machine through the normal brewing cycle and then add some fresh water to the Keurig and go through another brewing cycle again to wash the vinegar out.
When using vinegar to clean your Keurig coffee machine fill the Keurig with half water and the rest with vinegar.
Then run the Keurig through a normal cycle of making coffee but instead it will push the vinegar and water through the Keurig machine.
Then after that cycle finishes run some straight water through the Keurig machine again to remove the leftover vinegar and vinegar taste from the Keurig.
You don't want to have vinegar tasting coffee like I did one time when I failed to run the Keurig coffee machine through a second cycle to make sure it cleaned it out completely of the vinegar.
You can add just half straight vinegar as well without the water to really clean the Keurig but if you just need to clean the Keurig coffee machine just a little bit then using half water and half vinegar will work good.