Massive stars can evolve from birth to death in only a few million years if they are more than 50 times the mass of our Sun. It is expected that when the universe was very young, there were not many elements present heavier than helium, and without these 'heavy' elements, the typical opacity inside these young 'first generation' stars was very low. That means that as they are forming, they can accrete much more mass than modern stars do which have more internal opacity. The first generation stars may, typically, have been 50 times more massive than the sun, and evolved to supernovae within a few million years. The resulting black holes may have been so numerous that, forming clusters, the entire cluster collapsed under its own gravity to form supermassive black holes. It is also possible that the first black hole to formed, canibalized nearby stars and gas and grew at a rate of 1-5 solar masses per year or more.
Astronomers are not really sure how supermassive black holes form, they may even have been left over from the Big Bang itself as seeds around which the young galactic matter settled to produce the quasar phenomenon. The bottom line is that quasars seem to have formed within the first billion years of the Big Bang, and there are plausible mechanisms by which the underlying supermassive black hole could also have formed as quickly. The nearest quasar is 3C273 a few billion light years away, and this shows that the quasar phenomenon can still be 'turned on' even 10 billion years or more after the Big Bang. It isn't a specific object, instead it is a process, and this process may lay dormant for billions of years until something fuels it again.