You can apply for partner-sponsored Residence for him as soon as you can show 12 months' evidence of living together. Some of the evidence will be with INZ for the previous application, so send copies if you have them, with the previous application's details so they can see what was logged - make it as easy as possible for the new CO to tick their boxes. And keep collecting evidence while the new application is being processed, as INZ commonly ask for more just before the visa is granted, to make sure they're not issuing to someone whose relationship has broken up in the meantime.