When did the advertising campaign for Da'wah begin: Was it during the Hijrah, or during the secret Da'wah, or during the public Da'wah?

The prophetic call began secretly and lasted for three years, during which the Prophet invited his friends and relatives to the monotheism of Allah. Then, he declared it openly after the revelation of the verse: "So proclaim openly what you are commanded and turn away from the polytheists" (Quran 15:94). This marked the beginning of the public call. The call went through four stages: a secret stage for three years, then a public stage by word of mouth until the Hijra (migration), then a public stage with fighting aggressors until the Treaty of Hudaybiyyah, and finally, a public stage with fighting those who obstructed the call after being warned.