Well anytime you time travel and interact with the environment, if you think about it, you could create a new timeline.
Let’s just say you went to kill someone. If you kill the person in the past, then that past would completely changed. You are in the future of that past. Because of the butterfly effect, you could have been killed in any number of different ways. Maybe you just weren’t born. Then since you being born in the past still, it would end up erasing you. Or you just turn into a rip in the space time continuum. And even if you don’t die, your timeline could be extremely different. If you killed Hitler then pretty much everyone in this timeline would be gone.
So if a c**t decided to pop into my room saying they are me from the future, I would not tell anyone about anything at all. I would now know that time travel would be possible and invest in it. Once it is possible, I would got back to that same exact time and tell myself that. And if you went back it would be the same because you did everything exactly how it was done by the first you. And the first you is the present you, so you did do the exact thing. And when I get back i will come to a completely unchanged timeline. Wait ok hold on I might actually be on to something. If you did that with not f**k ups then you could change a lot of stuff. Something seems off tho. There is something else to account for.