Yes, you will reach there around 2 in noon, best way would definitely be to catch the earliest train..
Take 55361 at 7:00 am BC-PBE Passenger and you will be at PBE maximum by 9:30...then take 55373 PBE-TPU Passenger departing at 9:50 and you will be at Tanakpur around 11:45 am..
This is the fastest way possible..if you take bus till Tanakpur, it takes over 7 hours and you might not able to cope up scrupulous terrain.