When did the Scottish keyboardist Ian Stewart join the Rolling Stones?

Explanation

Ian Andrew Robert Stewart (18 July 1938 - 12 December 1985) was a Scottish keyboardist and co-founder of the Rolling Stones. He was dismissed from the line-up in May 1963 but he remained as road manager and pianist. Stewart was first to respond to Brian Jones's advertisement in Jazz News of 2 May 1962 seeking musicians to form a rhythm & blues group. Jagger and Richards joined in June the same year. In December 1985, Stewart began having respiratory problems. He went to a clinic to have the problem examined but suffered a heart attack and died in the waiting room.