The Gemara in Kesubos 62b - 63a, "Rebbe Akiva was a shepherd for Ben Kalba Savua. His daughter saw that he was modest and of fine character. She asked him, ‘If I marry you, will you go to the Beis Medrash to study Torah?’ He said to her, ‘Yes!’ He then married her in secret and she sent him away to the beis medrash...”
Avot D'Rav Nattan ch 6, mishnah 2. (summarized by DanF) says:
"... Once he passed by a well and noticed a carved stone. He asked who carved this stone, and they told him that it was the water that constantly dripped on it. From this, he said that if water was able to carve a hole in the hard rock, surely the words of Torah could carve his heart."
When did he encounter this stone? Was it after she sent him off to the beis medrash?