“At the time of Kriya, the tongue needs to be inverted and brought above through the nasal-orifice, cross the mucus membrane and it’s tip should be kept in a slightly tilted position towards the left side (this automatically tilts) ; and this state of the sãdhaka is called Kapidvaja, the flag or banner with a monkey.
For success in sadhana, one has to undertake or solemnize various karmas such as first kriya, second kriya, third kriya etc. as imparted by Sri Gurudeva.”
From Pranab Gita 1:20 and 4:12