When you are having a difficult time on a word or sentence; do you prefer when someone waits for you to finish or when they infer what you mean, and move on to the next sentence?

When you are having a difficult time on a word or sentence; do you prefer when someone waits for you to finish or when they infer what you mean, and move on to the next sentence? My landlords son has a pretty severe speech impediment and sometimes it looks almost physically painful for him to get certain words out, so I will naturally move the conversation along, for example; I have some furniture that needs to be thrown out and we have been trying to work out a date. He wanted to let me know he still didn’t know when it would be possible and would let me know at a later time, he was having a real hard time saying all this so I just said “okay let me know when you have a date” and left it at that but now I wonder if I have been rude all these years. He never seems offended he usually looks relieved but I would not know how it feels and want some more insight.