It starts from within. You need to find a way to be confident with yourself regardless and understand that you are not your stutter. It’s only something that you do sometimes. Think to yourself, if you were about to talk to someone and you KNEW for a fact you were going to stutter. Would you rather be at peace with the stutter or allow yourself to get anxious and nervous while beating yourself up about it? Ultimately you can’t control the stutter, you can’t control the other persons reaction. What you can control is your reaction to yourself. Show some self love and be patient. Stop viewing not stutter as an option and instead focus on the content your delivering. It helps out a ton. Not so much as with the speech itself but with accepting who you are.