My son got two years at 100% is it possible he might get out before 2 years

Please explain "two years at 100%". Judges do not normally use that terminology. They might say, "24 months, no parole", but the length of time that the offender ultimately serves is up to the Department of Corrections and the inmate themselves. If you follow the rules and are a model prisoner, most sentences come with 15% good time granted at the time of incarceration.