In the bulb world, crocus are considered pretty early risers and I'm not surprised yours are showing signs of life - I'd expect mine to be in bloom in the next few weeks. They are also extremely cold tolerant and will bloom regardless of weather conditions, even poking their noses and flower buds through light snow.

Forced crocus will grow and bloom very quickly if provided enough warmth and light.......as long as they have received a sufficient chill period in the frig.