Eye trauma - I have blood in my eye. Can it wait til tomorrow?

Depends. If the blood is on the white part, it is likely to be a broken blood vessel caused by holding your breath like with a sneeze, lifting heavy objects, etc. If the blood is behind the clear window go to the nearest emergency room immediately.
No. Traumatic eye injures should be evaluated immediately. Nontraumatic blood streaking in the eye may be from a small vessel bursting. However, if it is related to trauma then you would want to rule out globe or orbit injury that could possibly compromise vision.