Janko was born in Rogača, beneath the Kosmaj. In his youth, he mostly lived in Belgrade with his sister, who was married to a Turk. In this time he learned Turkish, which would benefit him later on. He, however, came to bad terms with his sister's husband and was forced to leave and return to Rogača. In the region, the Uprising was planned and he joined the uprising and was appointed as the "knez" of one of the former Ottoman nahiyah, and as he was known for being just, prudent and heroic, he quickly became the head commander of the Belgrade nahija. He had a good appearance, and in the assemblies, he was a good speaker, and in the battles, he was a very adaptive, adroit, and heroic chief. He was popular with the people, and his contemporaries called him "prude and heroic Janko". He was one of the most important figures of the First Serbian Uprising.