Each county has its own District Attorney and therefore its own parameters for the ARD program. If you have no prior record you may qualify for the ARD program. A criminal attorney who practices in the county your were arrested in can advise you on the parameters of ARD in your county. Many Counties also have Intermediate Punishment Programs which may help you avoid jail time. If you get convicted of First Offense DUI with your BAC, the mandatory minimum is 72 hours in jail and $1000.00 fine. You should have a criminal attorney represent you.
There are a number of options which you have. One, which allows first offenders to avoid jail, is called ARD. Basically, you are on probation for a period of time, and if you complete the program, the charges get dismissed. There is a license suspension, and some costs involved. You should sit down with an attorney to discuss this.
If you are convicted ( plead guilty or are found guilty after trial) of a first offense DUI with a .215 BAC you are facing a mandatory minimum sentence of 72 hours of confinement (to six months). How that confinement is served depends on a number of factors, many of which are peculiar to the county in which you were arrested and charged. If you qualify for a first offender's program - ARD, you may avoid any jail or house arrest. You should immediately speak to an experienced criminal defense attorney in your county. Good luck
Unless you are approved for the ARD program, there is a mandatory minimum jail sentence that you would have to serve. You can refer to the link I provide you to determine what penalties you would face in the absence of ARD. Good luck.