Firstly, there is obviously the time travel genre of story you might be writing in and, here, I'd ask have you explained how time travel works in your fictional world? Can everyone do this or is it limited to the privileged few? What happens when things go wrong?
Secondly, the era of your stories - what has made you chose this? How has the "past" you don't write about in your story influence the behaviour of your characters and the way the society they're in is run? I find it useful to know why the society is run the way it is. I don't put all of these details into my story (not directly relevant) but I use what I need to and the rest influences the way I write the other characters.
Is Time on your world the same as we have it here? If not, what has made you choose the system you are using? Do your stories show the downsides and advantages of this system? And how do your characters age and die - as we do in a linear way or not?
And talking of time, it is time for me to get on with my other writing!