There are screening tests for dyslexia that can be done by eg SENCOs which give a percentage chance of dyslexia and then EP assessments that can diagnose.
My ds is dyslexic and was diagnosed by an EP at a similar age. He also has dyspraxia which means it is hard to write as fluently as his peers.
Given that dyslexia is essentially a memory issue you are looking for memory things like
My suggestions for your SENCo meeting are
what symptoms does he show:-
spelling below that expected for his general cognitive ability
organisation difficulties
writing difficulties eg letter reversals, non-joined up writing etc
reading difficulties
What do they suggest by way of provision/therapy to reduce the symptoms?
typically this is learning spelling rules through the conscious channel, some writing exercises to improve the hand-eye coordination, and maybe some sessions on organisation - maybe this will be more important later when organisation is more crucial, but at year 5 90% of the stuff in the cloakroom clearout was ds's or his equally absent minded friend.
The other type of provision they should be looking at are ways of changing the learning environment to help dc thrive and habe a fair chance,
So ways of getting dc's thoughts down without having to be help back by the handbrake of dyslexia. How can dc think creatively and get the thoughts down without being distracted about spelling and letter reversals etc.
The most frequent option is touch typing and access to a keyboard. My ds learned to touch type at 8 - it is dull and he needed a lot of incentives to get the modules done, but it was worth it. It is easier to spell because the 'b' can't get confused with the 'd' because 'b' is on the bottom line and 'd' on the middle. Also if you have the spell checker set so that it identifies spelling mistakes and makes suggestions for alternatives, then the brain starts to pick up repeat mistakes and the correct alternative.
Some schools/parents offer to scribe for their kids so that the answer can go down untainted by the effort of recording.
Then reading - e-readers with the text sized magnified makes life easier, school providing large print homework or, more discretely one of those magnifying sheets. Lots of people have success with different coloured films to put over the page, or even work printed on different coloured paper.
And, probably for later, there is dragon dictate. I heard of a lass who could not write or read but is at uni with all her work recorded by dragon dictate and all her written texts dealt with by text-voice software.
Hope this helps
Good Luck