isnt there a rule that possessive pronoun should not be used before stating the noun that it is referring.

No, this isn't an absolute rule. You can use a pronoun before its antecedent. This is less common than using the pronoun after, and there are times when this setup is too awkward or ambiguous. But it is allowed.

Like those of most religions, Sikhism has codified its teachingS in a book

I did a search for this problem. It showed up in a Kaplan book, not OG10. Be careful about your sources!

Also be careful when you type problems / sentences. You were missing the "s" on the word "teachingS" and that makes a very big difference - without the "s," the problem is one of agreement (singular vs. plural).

And, sadly, I have to stop there, because Kaplan asked us not to comment on their material. I wil say that I would consider the above setup awkward simply because of how far into the sentence we have to go before we know what "those" refers to. If I do use a pronoun before the noun, I should get to the noun fairly quickly and not leave the reader hanging too long to figure out what's going on.