It's a federal sentence so she will be doing most of the time assigned. Each year of good behavior gets up to 47* days taken off the prisoner's sentence. IIRC, these are awarded at the end of each year in prison, so you can't just calculate 11*47 to get the reduction as if she behaves, she'll only be in nine and a partial year. She'll miss out on those last two years of sentence reductions.

* The law says 54 but in practice it's 47.