A couple of days is probably a tad too hasty. I cultured some using the same medium and it took around a fortnight, as greatwhthunter also stated. If you hold the container to the light you might see the surface of the medium 'sparkling' as the worms move. It'll be fairly obvious once they begin climbing the sides; they form vein-like clusters.
I read an article that stated you could place a piece of kitchen-roll on a section of the medium, on to which the worms would multiply, and then use a spatula or some such to collect them and subsequently use to feed them to your animals. Worked well for me; I'd began culturing in a container with comparatively less area on its sides than there was area of the medium, so using the kitchen roll became convenient. I'd started doing this after the medium was entirely covered in worms. There was enough to feed the 40+ young larvae I was keeping, and the worms still multiplied significantly and began climbing the sides.
Hope some of that is of some use.
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