Viewing from a point of single, unbroken timeline - it doesn't matter how far are you from your parents. As silly as it sounds - you could even pop up intin the room they are having sex in.
Why?
The key point here is the very first sentence in your question. If we assume there is only one timeline, killing you throughby sending you back in time will just not work. You are as you are exactly BECAUSE you were sent back in time (or not, depends if given person decides to do it. It really doesn’t matter, it happened.). Without Multiverse this paradox is simply unavoidable. Furthermore, the person that sends you into the past can just as well be killing himself - not immediately, but as you mentioned in some comments - the butterfly effect might have just as well killed him. Or made him never meet you. Or, or, or. The possibilities are endless. If you assume that traveling into the past will change the future - you just cannot avoid multiple paradoxes at once.