We're now doing Lidcombe program. SALT told us cut off point really was 6-7. Ds started exactly the same as yours, with kind of re-running the first words of sentences. It has now developed into an evil bastard of a stammer with up to 30 repetitions of a sound every 3 or 4 words. So please don't wait, get on list! SALT waiting lists here are awful. You can always come off if you don't need it. We have been td no face to face visits until at least Jan, but are doing Lidcombe program via Zoom.
We were told not to draw any attention to it that could lead to ds becoming self-conscious. He's happy to talk, albeit with a stammer, and that's better than claiming up. SALT drew the analogy to someone talking with an accent- not wrong, just different.
As pp said, try to slow down your own speech and don't ask loads of questions - avoid anything that puts additional pressure on his speech. Wait for him to finish by himself, don't finish sentences for him. Equally, don't say "slow down, no rush, take a breathe..." as they draw attention to the difficulty but apparently don't generally help.
Look at stamma.org for advice and support.
We were told to refer to "bumpy talking" as being perfectly okay, just another way of talking, but that we wanted to see if we could help smooth out some of the bumps to make it a bit more comfortable/easy for him. (Ds was late talking and makes up for it by talking the hind leg off a donkey!)
Lidcombe program involves ten-fifteen minutes dedicated "smooth talking time" daily, overseen by a SALT once a week. Really highly structured. We've been given pictures of scenes with lots going on and start by asking qs with one word answers eg what's that, building up to questions which need more words e.g. what's happening here / has anything like that happened to you? After every non-stammery response, the first thing you do is praise the smooth talking (not "good boy" or "well done" and not immediately correct a wrong answer.) As I say, you start with short answer as and build up - once they give an answer with a stammer, respond to the answer without referring to whether or not the speech was smooth. Comments on speech are only for smooth talking. Then drop down to a level they were okay with...so if they could say "walking home" okay but stammered on "crossing over the road" then drop back to qs with only 2 word answers and try to build back up.
We've only just started it, and it's yet to be seen how ds responds. I gather as program goes on, we then start to pick up on one or two bumps in a session, and then start to do smooth talking time for 15mins in everyday life. But only comment on speech during smooth talking time, not just throughout the day.
It seems to be all about praise, praise, praise so the brain build pathways saying "this kind of talking is good." With older children, it may be harder to build those pathways and it could be there's a different/better approach.