Update:
So here's the deal, time travel from what we know is not that simple, you would not end up in a specific area or time in the planet, you would end up in the ionosphere or further out because you have to account for planetary movement as well. So for example if you travel today to lets say, 1935 you will end up in a specific day, if you were to want to appear in a very close proximity to earth on the other side, make the correct plans. Anywhere closer and you risk dying.
So to recap you must account for 1. Time 2. Place 3. Alternate universe to be to be traveled to, now we know that there may be unlimited AUs so our only point of reference is us, so you start counting on 0.01 to 100, 0.01 being closest to being similar to us and 100 to furthest in similarity from our own AU. You must also be aware that you can only travel forward to stay in the same AU and be aware that traveling backwards is a one way ticket. Of course, your time machine must be able to be space ready. Risk management should be your second concern. The last and fourth thing to account for is Rules. 4. Rules, There must be a set number of rules which must be followed when traveling as to not disturb or change the history of the timeline traveled to, and a reason for traveling, no one ever accounts for this and it is very important, you cannot have travelers go out and about doing as they please, this could be disastrous. Not just anybody should be allowed to make these trips.