2. The interview must take place after you have completed the 3-month district requirement.
This is only true if filing up to 90 days before an applicant has met continuous residence requirement. Otherwise, the residency requirement must be met at the time of filing application.
ref: 8 CFR 316.2(a)(5)
(5) Immediately preceding the filing of an application, or immediately preceding the examination on the application if the application was filed early pursuant to section 334(a) of the Act and the three month period falls within the required period of residence under section 316(a) or 319(a) of the Act, has resided, as defined under §316.5, for at least three months in a State or Service district having jurisdiction over the applicant's actual place of residence, and in which the alien seeks to file the application;