What are the early indicators to help determine if a child should be evaluated for Dyslexia? At what age can the signs first be detected?
Dyslexia is more an auditory than a visual phenomenon it seems, and one of the early indicators is that kids that have a high chance of being dyslexic have trouble learning how to parse words into syllables, at age 5. But 'having trouble' means being worse than other, non-high-risk peers. I have no idea how good in absolute terms they should be, or how the game of parsing words into syllables is introduced though. But perhaps you can look it up more thoroughly based on this info. I heard it at a lecture on dyslexia, from a neuroscience expert.
According to the National Center for Learning Disabilities, persistent difficulties with reading, particularly coupled with frustration, are an initial indicator that you should be concerned.
More specifically, there are a variety of warning signs for each age group, and matching three or more of these signs should be cause for concern (emphasis on concern; always rely upon a qualified professional for actual diagnosis):
In Elementary School
In High School
All of the above symptoms plus:
Education history similar to above, plus:
I hope you don't take offense, but isn't this a thing to ask your pediatrician? Mine is great, and continually getting updated training, so I look to her for the most current information about things like this.
More generally, I would be watching out for other language-processing problems that aren't developing as quickly as you expect.