Was Jacob already a heart believer when the angels of God met him?
No. When the angels of God met Jacob, the context says he was aware of all that God was doing, yet he was still not a heart believer. He recognized the host and named the place Mahaniim, but that did not make him a heart believer at that time.
Les explains that Jacob was aware of all these things God was doing, but he was still not a heart believer when the angels of God met him. Jacob saw them and said, "This is God's host," and called the place Mahaniim, meaning the two hosts—God's host and his own. Later, Jacob sent messengers before him to Esau his brother, and then at the ford Jabbok he was left alone and wrestled with a man until the breaking of the day. When the stranger saw he could not overcome Jacob, he touched the hollow of Jacob's thigh, crippling him, and from that point on Jacob walked with a limp, called a halt in Scripture.