Hi, there are no guarantees for us worldlings (non-enlightened people) because we have accumulated anger for a long, long, long time, and the anger arises in response to frustrated desires which we have also accumulated for a long, long, time. But there is a move in the right direction, gradually, gradually, and then one day you realize you haven't lashed out in anger for ages, and that builds your confidence, and the progress intensifies. That's my experience anyways. But I'm always aware that there will almost certainly be one of my old road rage incidents, the accumulated tendency still lies lurking. But moving in the right direction is great!
Kammalakkhano , bhikkhave, bālo, kammalakkhano pandito, apadānasobhanī paññāti
(The fool is characterized by his/her actions/the wise one is characterized by his/her actions/Wisdom shines forth in behaviour.)
(AN 3.2 Lakkhana Sutta)