Having your own worm bin makes great compost, however, using your old soil to start or keep one going wouldn't be the best route. If you wanted to turn your old soil into compost you would probably need to make a good size pile of soil and mix it with a lot of fallen leaves and/or layer it with a bale of hay from the feed store that contains oat, alfalfa, barley and the like while also layering some amendments such as kelp meal and alfalfa meal. Mix all of it up really well and leave it until the spring and see what it looks like then. Most likely earthworms and other shredding insects would get into it and start putting in work breaking it down. As with most things, quality in equals quality out.