Hello
Thanks for your consult at DoctorSpring.com
Yes, it is possible for a psychiatrist to diagnose a case of paranoid schizophrenia within a two days time. Moreover, if the symptoms are clear, it may take a good history of 1-2 hours and a good mental state examination of one hour to diagnose a case of paranoid schizophrenia. Paranoid schizophrenia, if it's a first episode of psychosis then there is a 33% cure rate. The Rest of the cases persist but can be controlled with the help of medications. Eccentric behavior and short temper are not the primary symptoms of schizophrenia but are frequently noticed among the patients of schizophrenia.
According to the revised fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), to be diagnosed with schizophrenia, three diagnostic criteria must be met:

1. Characteristic symptoms: Two or more of the following, each present for much of the time during a one-month period (or less, if symptoms remitted with treatment).< >DelusionsHallucinationsDisorganized speech, which is a manifestation of formal thought disorderGrossly disorganized behavior (e.g. dressing inappropriately, crying frequently) or catatonic behaviorNegative symptoms: Blunted affect (lack or decline in emotional response), alogia (lack or decline in speech), or avolition (lack or decline in motivation)If the delusions are judged to be bizarre, or hallucinations consist of hearing one voice participating in a running commentary of the patient's actions or of hearing two or more voices conversing with each other, only that symptom is required above. The speech disorganization criterion is only met if it is severe enough to substantially impair communication.
2. Social or occupational dysfunction: For a significant portion of the time since the onset of the disturbance, one or more major areas of functioning such as work, interpersonal relations, or self-care, are markedly below the level achieved prior to the onset.
3. Significant duration: Continuous signs of the disturbance persist for at least six months. This six-month period must include at least one month of symptoms (or less, if symptoms remitted with treatment).