Yep. Obviously there's no particular date on which the Hunter-Killer groups suddenly became effective, but as far as I'm aware they began to assert themselves in late 1942 and became more and more deadly throughout 1943. My understanding (and it's limited) is that early attempts to form these groups were hampered by lack of experience with the level of co-ordination required and the relative unavailability of particular technologies - especially the Hedgehog thrower and HF/DF detection. These limitations progressively decreased through 1942 so that by the end of it the Hunter-Killer groups were beginning to hit their straps.