I'm assuming that you have an EE, not an Ameraucana, since you say you're looking for a blue or green egg and Ameraucanas lay blue eggs. I always keep at least 1/4 of my flock as EEs, and I don't expect my EEs to lay until 28-32 weeks. That means that your bird is on the very late end of normal right now. Add in the winter weather, and if you don't have supplemental lighting, they may not lay until spring. This happened to me once, but with dark brown Leghorns, not EEs.
In my experience, EEs are more varied in when they start to lay than other birds. I think it has to do with the fact that they are just more varied birds, since they are mutts. I'd expect more conformity from actual breeds of birds, like white Leghorns or Wyandottes, but even with them, they will vary by several weeks as to when they lay their first egg.