I found this on reddit, so far its been 100%
Welcome Pua, 2h
Pua, 4h
Sina (lvl 5) + Chief Tui (lvl 4), 8h
Build Moana's Boat (10000EC, requires Pua lvl 2), 8h
Chief Tui (lvl 4), 6h
Sina (lvl 5), 8h + Chief Tui (lvl 5), 4h
Chief Tui (lvl 5), 6h
Welcome Maui (unlocks 5/3)
Week Three/Four...