Gross development delay help

[Mum2elmo]

Hi all. Just as thought I'd ask some advice
My son is 2 1/2 years old he doesn't speak or realy communicate in any way or do most things a child his age can do. We had an appointment with a pediatrition a few weeks ago and has been diagnosed with a development delay. He's has his first speech therapy session next week but I don't know realy what's going to happen next.. Anyone else have any experience with this? I've not had it explained to me very well thanks all x