My ds had a schedule of growing skills done at 7 months and at 6 month intervals.
They look at different areas of development -
hearing and language,
speech and language(babbling, any words, understanding)
gross motor/locomotor(sitting, crawling, rolling, walking)
fine moto/manipulativer (pincer grip, holding crayon, holding small bricks)
social communication (eye contact, smiles, shared interaction)
self care (feeding, drinking, getting dressed)
they will ask you questions about what your ds can do, and milestones, and have some toys for your ds to play with - bricks, shapesorter, cups etc. They score on a sheet, and work out a developmental age in each area.
I think that is about it, but if you have any questions ask!