Hydrogen, helium, deuterium, and lithium formed in steeply decreasing amounts in the first few minutes of the universe after the Big Bang. These were the first 3 elements of the 92 in the natural periodic table, since hydrogen and deuterium are isotopes of the same element. The other 89 natural elements and their isotopes formed much later.

Carbon may have been present already in the interior of long-range functioning stars along the Russell-Hersprung main sequence, because it is needed to catalyze the fusion of H to He according to Hans Bethe’s scheme. But maybe in the first- generation stars, this thermonuclear fusion proceeded without carbon catalysis, because the first stars were hot enough.

In the usual view, all elements above boron were produced by dying stars whose cores had run out of hydrogen, just shortly before their explosion as supernovae. Beryllium and boron, and to some extent additional lithium, which are much scarcer in the universe than their predecessors, H and He, or their successors, C, N, O etc., were probably produced slowly in interstellar or intergalactic clouds as a result of bombardment by high-energy cosmic rays. (A pale echo of Hoyle’s now discarded hypothesis of continuous creation of hydrogen in such spaces as an alternative to the Big Bang theory, now generally accepted. )

First-generation stars were more massive than later ones, and burned out much faster, so that the first wave of nucleosynthesis at their deaths did not take too long, only millions of years after their births, not billions, as in later star generations. Later generation stars also already contained some of the heavier nuclei, like silicon, that could go into the formation of their planets, if they had any.