Answer
You cannot identify an exact moment when it happens. No one can say precisely when a person becomes free from sexual attraction.
Real freedom from sexual attraction comes only when you become positively attracted to the duties of Radha and Krishna. When you develop genuine attraction for devotional service, attraction to the flesh naturally diminishes.
At present, your gross eyes see only the external body, but the scriptures teach us to see differently. The scriptures explain that the body is temporary. As your perception becomes purified, you begin to perceive another reality. Your vision enters a different realm where spirit begins to touch your consciousness.
At that stage, material attractions naturally lose their appeal. Until then, because you lack a higher attraction, you have to consciously remind your mind, "This is merely flesh. This is not the eternal spiritual body."
However, when your soul begins to touch the transcendental form of the Lord and the transcendental sound of His holy name, your taste for material attractions gradually decreases. I am not even saying you are fully experiencing it yet—your soul simply begins to touch that transcendental reality, and the attraction starts fading.
Ultimately, the Lord must free you. Paramatma is seated within the heart. He observes how sincerely you struggle, and when He sees your sincerity, He frees you from material attraction by giving you a higher, positive attraction. Genuine detachment comes automatically through this positive attraction.
Continue struggling. Continue praying. Continue engaging in devotional service. One day you will naturally become free because the higher taste becomes obvious. As your relationship with Srila Prabhupada, Krishna, the Deities you worship, and the Holy Name deepens, all the sexual energy within the body becomes sublimated.
Sexual energy is fundamentally a creative force. It can be used in very low ways or elevated to its highest application. That same energy is required for higher realization. One cannot properly develop vijnana without following brahmacharya because that conserved energy is needed for spiritual advancement.
Initially, there may still be struggles. You may gain some understanding, but then lust arises and covers it. You fall, then rise again. This cycle continues. But there is a stage where attraction itself disappears, and that is the stage we should aspire to reach.
Krishna is describing all the intermediate stages. A person who has knowledge and realized understanding can still have both covered by lust and may fall. But a paramahamsa does not fall because he is already experiencing the transcendental form, name, and presence of the Lord.