Answer: As a general rule, it happens suddenly. There a process of zooming in and out from the Creator, but when His revelation happens to a person is unknown in the previous second.
Question: What does the person feel when this happens?
Answer: He feels a flood of Light in his mind and feelings, in his characteristics and understanding. The Creator is not a concept with some kind of pleasant feeling; rather, you begin to see the depth of His natural system and how it is moving.
The Creator is a system. So, it is possible to attain Him only through its operation on us, through our integration within this system.
From the Kabbalah Lesson in Russian 3/13/16