You can disable the time zone adjustment on the Effective Date and Expiration Date fields in the Price List Item. By default, the time on the Effective Date and Expiration Date fields is adjusted based on the Time Zone of the Locale in the org. If you disable the adjustment, CPQ does not change the time you manually configured in the Effective Date and Expiration Date fields. Refer to Adding Additional Details to a Price List Item for information about the Price List Item fields.