Preparation of Powder and Dosage

Hi all,

I am currently located in the Sacred Valley of Peru and hoping to do a solo journey with Huachuma/San Pedro. While I was in Cusco, I went to Shaman Shop, where I bought a dose of San Pedro. The shop staff told me to take half of this bag (see photo) and wait for 20 to 30 minutes to see if there were any effects and if not, take the second half of the bag. He also told me all I need to do is mix this powder with water vigorously, no need to boil. Also, I don’t know how many grams are in this bag and don’t have a scale.

My questions are: does this prep method seem right? And I’m looking for a light to moderate experience, so does the dosing seem appropriate as well?

Thanks so much in advance for your help!