First of all I want to tell somthing. Psychiatric disorders are broadly devided in 2 groups, i.e., neurotic and psychotic. Neurotic disorders are self detectable and approacing for treatment, while psychotic group disorders are not detected by self and these are detected by others, so that treatment approachs are from others/ attendent. Schizophrenia is a disorder of psychotic group. It is cognitive/ thought disorder. So, it is not easy to self detectable disorder. You can understand like, if a computer CPU booting programming has been disturbed then other booting software is needed to detect problem and to solve it. So, others help are needed to detect it as schizophrenia. Schizophrenia can be handled by the self motivation and environmental support. John Forbes Nash Jr. (June 13, 1928 – May 23, 2015) was an American mathematician, is a great example of schizophrenia, and he was awarded by nobel prize, because of his great work in ecomomic sciences.

Hello..there are no reliable ways to detect schizophrenia early..in the early stages you may expect some amount of confusion and odd behaviour..but there is no reliable criteria for that.