Following a community vote that took place on August 7th-10th, it was decided NG+ rules would be altered to permit visiting the HQ to adjust party members and equipment beforehand. Resetting in order to get the desired character layout used to be the major RNG-borne timesink of the category, hence this adjustment.

Current NG+ rules read as follows:

Timing starts upon loading a valid NG+ save.

A save is considered valid as long as it is created before entering the prologue battle. It is permitted to visit the HQ to adjust party members and equipment beforehand.

In case one finds this insufficiently rigorous, here's a very thorough rendition (courtesy of DoomyDoom):

Complete the main story using a pre-made NG+ save. Timing starts upon loading a "valid starting NG+ save", and ends when Maximillian's HP in the final battle (18b) reaches zero.

A "valid starting NG+ save" is a save that satisfies the following:

1. NG must be completed.
2. Any amount of NG+ loops may be completed, to obtain any valid in-game state.
3. Extra DLCs may be completed (Ruhm is allowed).
4. Upon completion of points 1-3, a new NG+ should be started.
5. In this new NG+ it is allowed to access HQ and perform any possible actions therein. It is not allowed to complete Prologue battle (or advance the book mode chapter in any other way).
6. After completing HQ, a save should be made just before Prologue battle.