She doesn't need to be able to read to write no. The O's are a very usual form of first writing. The child is representing text as she sees it. It will evolve to include other shapes and eventually recognisable ones. I would recommend teaching lower case rather than capitals as this is what they will need to write primarily in to begin with.
Foster her interest by pointing out written words in everyday life. You could focus on the first letter of her name and find things that start with that and cut out pictures and paste them with the letter. Big is better for little hands so get her some of those thick colouring pencils.
they will teach the correct way to write the letters at school, so if you can try eventually to move towards that, it will help her once she gets there. I'd focus on her name and other family for now.

What a clever chicken, btw, as this is quite early to be 'writing'.