GOD knows what you should say and When! This is what Jeremiah said when GOD called HIM!
“Then said I: “Ah, Lord GOD! Behold, I cannot speak, for I am a youth.” But the LORD said to me: “Do not say, ‘I am a youth,’ For you shall go to all to whom I send you, And whatever I command you, you shall speak. Do not be afraid of their faces, For I am with you to deliver you,” says the LORD. Then the LORD put forth His hand and touched my mouth, and the LORD said to me: “Behold, I have put My words in your mouth. See, I have this day set you over the nations and over the kingdoms, To root out and to pull down, To destroy and to throw down, To build and to plant.””
Remember that GOD knows you better than anyone.
Jeremiah 1: 4-5
“Then the word of the LORD came to me, saying: “Before I formed you in the womb I knew you; Before you were born I sanctified you; I ordained you a prophet to the nations.””
GOD told Jonah the same thing when He asked Him to preach at city Nenevah.
“Now the word of the LORD came to Jonah the second time, saying, “Arise, go to Nineveh, that great city, and preach to it the message that I tell you.” So Jonah arose and went to Nineveh, according to the word of the LORD. Now Nineveh was an exceedingly great city, a three-day journey in extent. And Jonah began to enter the city on the first day’s walk. Then he cried out and said, “Yet forty days, and Nineveh shall be overthrown!””
Jonah 3:1-4 NKJV