Board Thread:Questions and Answers/@comment-24731329-20150303101022/@comment-460323-20150303132321

It really depends on you. Ideally you'll want to level your ships a bit more since the later maps will keep wrecking your ships and make you lose quite a lot of resources/buckets. If you've yet to collect all the Kongou-class and unlock your fourth fleet, consider grinding world 2 or 3-2.

Or if you're lazy, you can just complete 1-5 now to get medal and huge HQ level boost while the boss is still weak. Remember to develop sufficient ASW equipments~