ahh i know the frustration. when i was in teh hospital for two months, i could ONLY lay on ONE particuar side for over a month...this was prior to surgery, but nonetheless, i know the discomfort..
id go with what everyone else says also...do it when it feels ok....use a body pillow maybe? thats what i did/do....put one end between my legs/knees, then sort of line it along my body/tuck it between my body and the bed, and then hug it with my top arm! my body pillow is really worn and flat now though, so it may be easier said than done with a nicer/newer one.
also, the one behind you will work great...even better if you can get someone to really tuck it in under your back.