It may be useful to keep in mind that at least in modern quantum field theory, individuals are emergent. Namely, quantum fields are primary (even if you "see" individual particles in those Feynman diagrams), and the appearance of discrete individuals is an emergent phenomena. Put different, and here Steven Weinberg's The First Three Minutes is particularly nice, as the universe cooled down from the Big Bang, the various individual particles we now see emerged, much as the orderly crystalline structure of ice emerges as you cool down water. In the Big Bang, where time is measured in terms of the exponent of the time after the Big Bang (10^t seconds), where t is a negative number (for most of what interests Weinberg, and goes as high at maybe +2 in his book, but see next paragraph) and is that time, the earlier times are too hot for individuals to emerge and be comparatively stable objects.
As for time, that t in that last paragraph, it takes some time, say when t is about +16 or 17, that is, billions of years, for the stars to form, supernovae to explode, the heavy elements to form. The universe is something like 13.8 billion years old, I believe, and so t is now about 17+.