Hi BamBam
There's no guide on the packets because it's up to you.
I did mine in a large mug,also like a cup a soup.
If you like to get it down quick make it thick with less water.
If you want it to last then make it thinner with more water.
You can mix 2 packs together if you forget to have one or run out of time. Basically you can do what you like as long as you have all the packs and drink plenty of water.
You'll soon get into a routine.
Good luck x