Originally Posted by **********

I am Mark-A.

First thing I would do is get a second, smaller, time machine.

I would put the small time machine into the larger time machine, hide it in a warehouse where no one would find it.

On the day I go back in time, I go to the warehouse and wait 15 minutes, at the front door. I then enter, Transport myself and the smaller time machine back 1 month.

Step out of the time machine, Become Mark-B Take the smaller time machine and place it in another warehouse next door to the first.

While back in time, buy lottery tickets that payout weekly. Pay cash for everything. Avoid cameras. Stay off my cellphone. Stay off the grid. Avoid running into myself (Mark-A).

Take winning tickets. Hide them in a place where only the A version of myself will find them, but only after the date of my departure back in time.

If I screw anything up, use smaller time machine to go back again, but be careful to arrive only after Mark B arrives (I would now be Mark C).

If all goes well, grab smaller time machine, place into larger time machine, return to the present, 15 minutes before I left. Exit through the back door so that I don't meet myself coming in. Hide from myself (Mark A)

When Mark A goes back in time, proceed to place where lottery tickets are hidden. If I was careful, I am in the same universe that I was in when I left, and I'm now rich. If the tickets are not there, I've made a mistake and created a paradox and am now in the wrong universe. Oh my god I've gone cross-eyed.