If 2 days after yesterday Monday 13th, then 1 day after yesterday is Sunday 13th and yesterday is Saturday 11th.
That means today is Sunday 12th and tomorrow is Monday 13th.
1 day after tomorrow is Tuesday 14th and 2 days after tomorrow is Wednesday 15th.
Now let's see. If you are traveling away from the sun at a speed approaching light speed and being observed from the Andromeda nebula, it would be about half past Thursday. Now two days before that ..........