I will be leaving from haridwar to joshimath. It's a journey of 10 hours and in between the journey you will witness the four prayags.
I will advise you to take bus at 4:00 Am. The bus will be at haridwar railway station and it will reach joshimath around 2:00 pm. The best part of reaching earlier is that you can also visit and explore some of the places in Joshimath.