Are you serious?
You will not simply die after slitting your wrist. In fact you need an incredibly precise plan just to have a small chance of actually succeeding. Your body will not let you bleed out through an open slit on the wrist. Blood coagulates. You panic. You regret. It's all part of SI. Not to get into how unbearable the pain is, how hard it is to get the placements right and the torture you need to go through as you sit in a puddle of blood.
A more reliable placement would be slitting your carotid artery, and even if it's easier to pass out and the bleeding is more intense, death caused by this is unrealistic to achieve by yourself without blood thinners, opioids, alcohol and a few more factors.
I suggest you reconsider.