Hi Reshu, we went in mid December and it was already challenging for me (first time trekker) without the snow. I have heard that Mar is a good time for Triund and snow subsides by then but I am not the right person to guide you on that. Hopefully someone who has visited during this time can help you.. hope you enjoy your trip though! :)
You can take the following route Chandigarh>Khajjiar>Dharamshala>Kangra Valley>Mcleodganj>Bir. Let us know your final travel plan. Happy and safe travel!