If you have already named your brother in family information form and have a connecting flight from toronto to new brunswick even if its a week or two apart and your employer is okay with it then it is within your rights to do this.
Now let’s be practical when you will land in canada as a PR their is a rare chance your flight will land in new brunswick directly. You will land in toronto,vancouver,montreal,ottawa first and go through CBSA. And when CBSA triage landed immigrants we have to give them our contact address where they will send our PR cards. We can call them later via phone too but still we will need a contact address. If CBSA officer checks your travel plans and their is no connecting flight ticket and no address for PR cards in NB they may become suspicious of your intent. So please don’t give (outside of NB address)for PR cards. COPR means nothing if CBSA is suspicious of your intent they still have the right to refuse you entry. Its better your brother should come to NB and after your settlement you may visit your brother. You can be lucky if CBSA don’t suspect you of dual intent,but it can be a hurdle to future AIPP applicants.
Thanks