There is a statutory mandatory minimum for a DUI conviction. If it is your first it's 48 hours in county jail. But don't panic. Your arrest and the night you spent in jail will count as one day. For the second day many counties will book and release you which only takes several hours.
Some counties do not impose the mandatory minimum but will charge more in fines. The amount of fines for a 1st varies greatly from county to county. Some counties are at or above $2500 w/ assessmants and some are around $1500 with assessments.
Each county in California maintains different standards as to whether or not a first time DUI offender needs to spend time in custody, as well as whether community service will suffice or if ankle monitors will substitute for custody.
You need to contact a defense attorney in the jurisdiction in which you received the DUI as soon as possible. Aside from the implications in criminal court, the DMV will take it's own action against your license. You have a limited time in which to contest a license suspension, so don't wait to contact an attorney for a free consultation.