I just push them into the surface of compost so the shoulders of the corms are about level with the surface. It's rather early for them yet though. It depends where you live, and you give no clues about that, but you won't be able to put them out until late April at the earliest in the UK - after the last frosts in your area. If they're sprouting now I'd try to find somewhere a bit cooler to store them in and start them off indoors about mid March or so. They're frost tender, so protect them.