Observing reactions and responses to any and everything was helpful as we worked with our non-speaking grandson. He was able to develop his use of sign language (customized to his fit his limited motor skills). This led to associating those signs to pictures using the PECS and now at 10 he is using an AAC (electronic PECS) device for most of his communication.

We label verbally and we use a form of PECS. If you want to start without an SLP, you can look it up and try both actual photos and generic pics to see what he responds to. I would start with the cards at least 2x2 or even bigger to get started.

Thx, do u use visual cards? How do u label

Label. Label. Label! As you speak to your child label things so that they start to associate.

I agree
I was told my youngest would be non verbal. I bought the book called Baby Signs (or something like that) and photocopied all the pages. I tapped them to a large wall in our kitchen. We used babysigns whenever we were speaking with him. Eventually he reciprocated.
When using the signs , always slow down your pronunciation of that word into sylables.
Ba na na. And make sure you dont add too many other filler words. Stick to the vocabulary so that word is the dominant word. Always say it the same way while using the sign. He will see you standing at the wordwall to find the sign. That will reinforce that communication and connect language to signs. He might eventually go and stand near the Word Wall and wave his hands around if he is trying to communicate. Pay attention to his related behaviour and adapt to him.
Hope this helps.