THe plant will show their sex in veg if they become mature enough in veg, a 9 week veg with certainly yield a mature plant. Auto-flower is a specific type of genetic trait of cannibus ruderalis-- it isn't something that just "happens" to any ol' plant out there. It's an autoflower if you bought an autoflowering seed, otherwise highly unlikely. Some plants are bred with one 3rd generation auto-flowering plant to create a very fast flowering, but still somewhat photoperiod sensitive and able to be cloned. I have grown both a Rasperberry and Blackberry Kushes from local clones that where like this and finished in around 7 weeks.
Simple version: If it is an autoflower just keep doing what you are doing, if it is not one just keep doing what you are doing.
I'd maybe try to top that plant though, if you aren't going to flower too soon.