April May have traditionally been good for Kimbe/Fathers also Late Sept Oct and Nov.
The windy months July August not so good for this area, Alan Raabe has been operating boats here for many a year and has his schedule down pretty good now. So long as his Captains follow his advice the trips on both Febrina and SD are good. Jan and Feb he takes the boats to the south coast of West New Britian where the diving is very different from the North Coast. The South Coast is not for everyone but for those that like Jurasic Scenery and hunting for weird and wonderful stuff it is well worth the trip. On one of the rips I ran to tnhis region we found a rare juvenile African Pompano Trevally along with aw fish, cuttlefish, arrow crabs, orangutan crabs, leaf scorpion fish, rock mover wrasse, pipefish, anemone fish, holothurians, banded shrimp, lionfish, scorpion fish, crocodile fish, ghost pipe fish mating octopus etc.
Each year they are finding something different. My Favorite trip would have to be a fathers/witus combination which includes a number of dives at the legendary Krak-A-Fat reef which has shark action, a huge school/s of trevally and barracuda as well as other fish life combined with a stop at Dickies place it was one of the best trip programs/schedules I have ever done as it had something of everything (even most of the time a sort snorkel with the dolphins at Fathers reef).
Craig the guy the runs the Golden Dawn also picks his schedules as good a possible for the areas he operates in have a look for space on a schedule that goes to Portlock reef as well as Eastern fields.
If you are into a little of day boat diving do not overlook Port Moresby as there is some fantastic diving to be had here as well and well worth spending a 2-3 days here. Either Dive with Loloata or the dive centre (the later based in POM and operates out of the Airways hotel), in Particular Susies Bommie, Pacific Gas (a wreck at max 34 metres), End Bommie, the pinnacles, Pai II, Baldwins Bommie are excelet to name just a few.
To do both south and north October, November should suit so you could do (if space avail) both the Stardancer and Golden Dawn.
IMHO PNG has absolutely fantastic diving