My son worked with a speechie on two separate occasions for stuttering. First time he was probably 3 and half and the second time probably 5. I'd say it took us about two-3 months to notice much difference. That was seeing her fortnightly and doing the homework for about 20 minutes each day picking up in it through the day. It did come back and we worked through it again. He's 8 now and his speech is fine and you'd never know. It did take a long time to see results. We called it smooth talking and if/when he didn't stutter we would praise it (great smooth talking/ those words came out really smooth well done) and lots of encouraging too slow down. I think a lot of my sons stuttering was caused by anxiety so we tried really hard to keep things calm for him and once he noticed he was getting smoother he came along quite quickly. Just keep at it - she'll get there soon.