Throwing out ideas. It is interesting coming up with origins for things. You don't really need a solidly defined age since things are potentially different for each character. I was merely presenting options outside the box of human years. You can come up with entire logical or illogical methods based on culture or physical phenomena. A species could even not be space faring, and simply have been picked up by others and yet to have a concept of time other than being. Or have a religious view that transcends time making it irrelevant.