The second main finding of Blossfeld and Timm's Who Marries Whom? is that educationally homogamous marriages are most likely in the years after school ends, then tapers off – especially for women. For high school women, there is a rounded spike of marriages to high school men in the late teens/early twenties. For college women there is a sharp spike in marrying college men right after college, then falling off. The college women seem to be catching up on the marriages they postponed because they were in school. For men, the pattern is similar, but not as pronounced.
The longer you wait to marry after graduation, the less likely you are to marry someone with your same level of education.