Firstly, understand that time is an illusion. Humans count 86400 seconds (1440 minutes or 24 hours) to make up one day and that is what is called time. Time is just numbers people give to different moments of the existential plane. So you cannot really talk about the age of the universe or whatever when really time as we know it is an illusion. I think that there is another concept beyond our reach in this dimension that would be more suited to talk about what you people call time.
Secondly, time did not come into existence. Think about what people call time travel. You are different from what you were 10 years ago physiologically not because of time but because its a physiological process. Time is an illusion. I like to think of it as an adjective rather than a noun. I see it as a description of something rather than something in its self. So you're wrong when you talk about 13.7 billion or whatever. That is a concept that is still miles away from human understanding.