You should apply at the beginning of each calendar year for the upcoming fall and spring semesters. The deadline for this past school year's fafsa is June 30, 2009. So you could have completed either one when you did it in January.
If you applied in January it could have been for this past school year or for the coming school year. Go online to FAFSA and see which one you completed. If you haven't done one for the 09-10 school year, you can pull the information from your last year's fafsa to your next year's fafsa. It's not too late.