how many weeks or months should my plant be before it starts flowering or sexing?

What lights are you using?

 

could be the pheno, or its cause of colder climates, it's perfectly fine

 

have you changed your light cycle to 12/12? If not, you've vegged them long enough (to the point you might even see pre flower hairs) to switch then you'll see their sex show 1-2 weeks on average.