As you identify when and why, then, if possible, try to avoid the situation or at least anticipate the situation. If you are irritated when someone is late, prepare yourself ahead of time before they arrive so that the negative emotion is controlled. Our thoughts and attitudes do determine our feelings and our actions. Claim God's help. Perhaps some of these verses will help to focus you on God's desire to help you.
Old things are in the process of passing away, behold all things are in the process of becoming new.
God is in the process of making you into a new creation. Agree with that process. Draw on the scripture. As the Holy Spirit works in you He will move you toward controlling those negative emotions.