From the deluded perspective, delusion begins at the moment at which we first mistake the coiled rope for a snake, and we are liberated from delusion at the moment at which we recognize that the coiled rope is merely a rope and not a snake.
From the deluded perspective, then, there is a period of delusion, and there is the need to be liberated from delusion.
However, no matter how strongly we believe that the coiled rope is a snake, the coiled rope itself is never transformed into a snake by our delusion. It remains a coiled rope. That is its nature.
Similarly, although we mistake the luminous clarity of the mind to be the eight consciousnesses and their delusory products, the mind is always empty and clear. That is its nature.
Even when we do not experience that luminous emptiness, it is always luminous and empty. The delusion may be there incidentally, but the fundamental nature of the mind never changes. The mind is always free.