We've got a look at what's on the docket for Danny Masterson for at least his first 90 days in prison ... and it looks like the disgraced actor will be on a short leash.

According to the official procedures for the prison, Masterson has to go through a reception and classification process that started Wednesday when he entered North Kern State Prison in Delano, CA -- a process that could take up to 90 days.

TMZ has learned ... during this time, Masterson will be in what's called privilege group U, and there are strict restrictions ... including no family visits, limited entertainment access and no access to personal property.

According to the CA Department of Corrections, he also gets one phone call within the first week of entering the facility, and then for the remainder of his time in group U he only gets one call per month.

He still has access to things like the yard and recreation services, but he won't get his full prison privileges until the classification process has finished.

Sources close to the situation say Masterson demonstrated "exceptional strength of mind and spirit" during his time in the L.A. County jail ... prior to his transfer to North Kern, and he's feeling hopeful about his chances of winning his appeal.

TMZ broke the story, Masterson was transferred to the prison, where he'll serve his sentence of 30 years to life ... following his September conviction on 2 counts of forcible rape.