Please help me be respectful to my new bf who stutters

Please help me be respectful to my new bf who stutters So i recently got a boyfriend who happens to have a stutter. Its not very heavy (he said he's had speech therapy for years and it used to be much worse). Usually just one word every few sentences he gets a bit stuck on. Now, ive never realy interacted much with people with a stutter. Just a few times, a friend of a friend at a party or something. And since im usually shy with people i dont know, there wasnt much interaction there. I have heard once that you should never try to fill in the sentences for someone that stutters, so ive avoided doing that. I assume this is correct? I do have ADHD, and sometimes in can cut people off mid sentence, its a bad habit and i reeeealy try not to. But bf and i talk loads and when i get excited about a topic i can get a bit more "dominant" in a conversation. But i try there. What i would like to know mostly, are there any (big or small) things in conversations with someone who stutters that i should or shouldnt do? Are many hand gestures perhaps distracting f.e.? As said i have spoken to him about it a bit ofcourse, but its a very new relationship, so perhaps he isnt comfortable pushing back on me yet about this part. And i would like to prevent hurting him accidentally. Thanks! Tldr; is there anything in a conversation with someone with a stutter that i should be aware of doing or not doing?