Early intervention is crucial. Research has shown us that people who receive treatment for their psychosis sooner have better outcomes in responding to treatment and recovery. See the 'Could i just ignore it?' section for further information.
There are various treatments recommended for psychosis, and guidance states a combination of treatment provides the best outcomes.
https://www.psychologytools.com/self-help/psychosis/
https://www.cci.health.wa.gov.au/resources/looking-after-yourself/bipolar
https://www.getselfhelp.co.uk/psychosis-clock-for-early-intervention/