First, get into a time machine and cyrogenically freeze yourself and go into the past.
Set the freezer to wake you up five minutes before you get into the freezer, so
you can wish yourself good luck.
You would know if it worked or not by whether or not you showed up to greet yourself. If you don't show up, you probably shouldn't go, but perhaps this is the reason you don't show up, because you decided not to go because you didn't show up.
So would you go if you didn't show up to greet yourself?