Armageddon and its aftermath: dating the Toba super-eruption

No-one alive today has witnessed a volcanic eruption remotely as big as the Toba "super" eruption. But our ancestors may have done, tens of thousands of years ago, when northern Sumatra exploded, creating a caldera now filled by the largest volcanic lake on Earth, measuring 100km by 30km and 0.5km at its deepest. But when, exactly, did it happen?