It would be a bit difficult to precisely find out, but what could possibly be the song where James starts to sing the earliest, and the latest?
For the latest, it's probably Octavarium, followed by In the Presence of Enemies pt 1. But which song has the least amount of time from the start of the song, to James starting to sing? Take away my pain? any of the simpler, shorter songs such Wait for Sleep or I Walk Beside You? if live versions count, it's Take away my pain off Once in a Livetime, he literally starts the song by singing and the others coming in.