What's the best time to visit Mussoorie to experience a snowfall!?

I work in Delhi, the usual 9 to 5 (which is definitely not how it sounds, iykwim) and so it's tough taking out time to travel. The aim is to experience a snowfall every winter and so we often try to rush to Mussoorie. But honestly, I'm 0 for 5 in the past 3 years. And even before that, I've only found a teensy bit of snow up there. Can any of the native pahadi peeps let me know what's the perfect time to experience and actual legit snowfall in Mussoorie!???