The process is different in every local authority unfortunately, so no-one can give you a definitive answer - unless you post where you are and happen to be seen by a poster from same area.
I could tell you what happens here, but it is definitely not the same as surrounding authorities.
In essence though, I think it is really worth while to write down everything that you d, that is an adjustment in some way, for your dd. Think carefully, as much of what you do becomes habit, and you don't see it as an adjustment.
It is really easy to forget to mention things otherwise.
Where you can, try to be as 'numeric' as you can... eg 'we hear these 6 words, in context, fairly often' rather than 'doesn't say much'. Or - just as an example, if she were a fussy eater, rather than saying she is fussy, say "She will eat all ''dry' foods but doesn't like any sort of sauce and doesn't like foods touching other foods" . or 'When offered a choice, she repeats the last word you said' etc. If she has distrubed sleep, write down the 'typical' night she has. 'Sleeps through' means different things to different people. Try to avoid words like "some" or "not much" as people have different perceptions.
If she attends Nursery, then ideally get them to fill in a developmental profile and / or write a bullet point list of what she can do and what she struggles with.
It just gives the paediatrician and SaLT so much of a head start when they meet someone for the first time.