Lie on side or on back during flush?

Hi all,

I'm doing my 3rd flush this weekend and wanted to know whether it's best to lie on my side just after taking the olive oil/juice or flat on my back?

During my first 2 flushes I went on my back and this seems to have worked OK but recently I read that it's best to go on my side instead to help the stones flow out.

Sorry if this has been covered before.

Any advice guys?

Thanks.