When did you first spot signs of colour blindness?

[Thistledew]

I know in reality it is way too early for me to tell if 20 month old DS could be colour blind, but I'm curious to know when other people, possibly with the benefit of hindsight, first spotted signs that their DC was colour blind. I do have a brother who is colour blind so there is some reason to wonder if DS is the same.

He is doing well with his language: he accurately uses some adjectives "big" and "baby" (i.e. small), "hot" and "cold". He can accurately identify "pink" and "purple" as colours, but describes all red, blue and green things as "green".

He will spontaneously try to identify colours but still names everything as "green". For example, the curtains in his room have green, red, yellow and white hedgehogs on them. He will point to both the red and green ones and say "green". Today, he saw a new toy which had blue and green blocks on it. He was pointing to both as "green".

I would be quite happy to be told this is all perfectly normal, but can't help wondering if he is genuinely struggling to differentiate the colours.

I also look out for colour blindness in DS who is currently 3 as DH is colourblind. He is good at colours and can name most of them however I mentioned it to the optician when we were having his older sisters eyes tested. She said they can learn colours but still be colourblind. She suggested bringing him for a test when he could recognise numbers well as the colourblind tests are all numbers.
When he was younger (maybe around 20 months but I can't remember) he used to say everything was green but I think he just thought green was the answer to the question "what colour is this".

Hard to tell at that age - you could try sorting objects by colour as that just tests matching rather than naming. My 3y7mo has confused yellow and green since he started talking about colours - when he's a bit more reliable at recognising numbers I will get an optician to check. However he does object if I give him a yellow bowl with a green fork or vice versa so I'm hoping it will be ok!

Thanks both for your replies. He does have a stacking game that matches colours and he can do that with no problem but he might just be matching the shades. Sorting his toys by colour might be a good test as there are different shades within each colour. He is just getting to the stage of being interested in games with rules so he might now take to it. He is definitely interested in colours as he is always trying to point them out to me. He was delighted today to find a stack of plastic boxes which had alternatively green or purple lids, and so he could correctly describe them!

My ds (5) is colourblind. It runs in the family. Early signs were that he learnt his shapes, etc well but really struggled with colours. He couldn't, for example pick up the red square even though he knew what a square was.

We knew for sure when he was about 4 and said things like 'which one is orange?'