Most creationists believe these to be 24 hour days. The other scientist will try to lengthen these days to fit the theory of the very old age of the earth. Another important point is that some events of creation are not in the expected order if long periods of time were involved. While many Christians say that evolution doesn't concern them because it's only a theory, a theory is regarded very highly in the experimental science world. Evolution should not be a theory at all.
Evolution is split into two parts, micro evolution, and macro evolution.
Micro evolution is observable and is the process of limited variations among individuals of a given species that produces verity. This does not fit the requirements of a theory. The object or phenomenon that is to be in a theory has to be observable. Secondly, the object or phenomenon of a theory must be testable. And the Spirit of God moved upon the face of the waters.