It is gradually
If child not will be able to say any sound, you should refuse from this way.
Let the child say this sound l actually y or not clear vowel it is more accurate so that it got to it on a palm.
The exhalation has to be hotter.
It is gradually necessary to remove a palm far away from a mouth, that re the benok strengthened an oral exhalation.
Saying a sound, the child has to feel how air passes at it between teeth.
Watch that the child had shoulders are lowered, and in muscles there was no other tension and clips.