Good that you already received answers.
In my experience, the preparation doesn't seem to alter the outcome enormously.
My quantity varies 1-2 tsp ES to a cup of water, sometimes spaced with ginger.
Is is not compulsory to induce diarrhea at bedtime hours. So ES can be lowered to a 1 tsp per cup and you will sleep better.
Olive oil is the one I don't like, but good mixing with citrus juice will help.
It is important to get them out quickly so one needs good quantity of ES next day.
Think about this: some of the "outcome" may be liquid instead of stones, so the Liver-Flush can be a success with minimal stones.