Paediatric neurodisability assessment?

Hi

My son's currently being assessed for ASD and the next step in the process is a paediatric neurodisability assessment (tomorrow). I've no idea what to expect and wondered if anyone's been through similar and could give clues? There's a questionnaire that asks when he first smiled, babbled, reached for objects. I really can't remember as he's 12 now and my memory is appalling. It's a 1 hr appointment and I'm terrified of missing something. We then have an appointment with a private assessment company that CAMHS have passed us on to (can't get them to return my call to book appointment which is frustrating) and that will be it. 

Thanks for any advice or info.

Ellie