I'd recommend still going through with the morning after Epsons. I don't know why their recipe doesn't suggest it. The stones might already be out of the gallbladder and bile ducts, but you still want them out of you ASAP.
I don't think it matters how much cream and berries you eat. I'm not even sure it's completely necessary. I'm not crazy about it either so this last flush I only drank about 2-3oz of cream and ate about a cup of blueberries and had a decent amount of stones. They don't have to be combined.
Not much difference between that amount compared to when I've drank more. I've also seen other posts on here where people said they actually got less stones out anyway using a lot of cream. Something about not enough bile buildup left by the time they drank the oil.