Moderator Post (s) for this thread: >Link:bydoug seibert on 04/14/2005
Many people never seal cement, and it lasts for about 50 years. I don't know how long it is suppose to last if you seal it from time to time. I don't think much longer than that. It just gets weak after so many years.
Nowdays, it is popular to seal concrete about 30 days after it was poured (once it fully cures). I think this helps to keep the dirt out. It makes it prettier (cosmetic reasons). I don't know if the sealer adds anything to structural integrety? It may help keep water out and prevent cracking in Northern freeze-thaw climates. However, if the cement was poured properly, it should not crack without it.
It certainly cannot hurt to put sealer on it. You would want to clean with TSP and/or muric acid first, or follow the directions that come with the sealer. I think if you wait until next year, no harm will be done.
Find out what the sealer products recommend. I personally would not seal it.