The yeast in the wort won't throw off the OG reading, so you were probably accurate.
I'd leave it in primary until it's done fermenting, and then about 3-4 more days. It might be about 10 days or so, but it could be longer. You want to get to FG before even thinking about transferring it, and I like to leave it on the yeast cake about 3 days after that. Even after fermentation is over, the yeast are still working. They "clean up" after themselves, even digesting their own waste products (like diacetyl). A bigger beer may produce more off-flavors at first, so I'd give it a bit more time.
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