Either one is OK. Just pick the one that you are most comfortable with.....

Pualette

I understand people in this forum have different opinions but I myself have tried different positions(In one occasion I stood up for a couple of hours) after taking the combo but for me the best results always came after I had laid on my right side.In fact, that is also the recommendation of Mrs Chang from Sensible Health.
You can try different options and see which one works best for you, and I can assure you that for me when I lay on my right side i definitely push more stones.

Good luck

Fernando