Explain when did life begin? (Scientific theory)

The earliest life forms that we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7 billion years old. The signals consisted of a type of carbon molecule that is produced by living things

What science say about origin of life :

The origin of life on Earth is a set of paradoxes. In order for life to have gotten started, there must have been a genetic molecule—something like DNA or RNA—capable of passing along blueprints for making proteins, the workhorse molecules of life. ... Now, researchers say they may have solved these paradoxes.

If talking about Big Bang i don’t know I read it wrong but I’m not deleting this because I’m not feeling up to it right now : )

Big Bang Theory.｡oO┌(;￣◇￣)┘

In basic terms:
An atom exploded and made everything.... but keep in mind...( energy cannot be created not destroyed)

The scientific theory: