how long can it take until you will know the sex of your plant?

I have 2 indicas 1 is 3ft tall and the other is about 2ft tall.
I beleive its been close to 3month's and I am not seeing any signs of male or female they are thick bushy and very healthy and they are slinky as hell but the signs that you look for to be able to tell just are not there? These plants are out door grow. Please, any insight would be great.

I started my first grow a little over a month ago(indoor) and two of my three plants I was able to presex(1 male and 1 female) before I switched the light cycle to 12/12. As far as outdoor I have no idea. My veg light cycle was 18/6, and around 30 days the preflowers were showing. The female is a Mazar-Sharif the leafs look more indica but it stretches like a sativa. The male is a Super Skunk mostly sativa.

August

Where it says slinky as hell lol its supposed to say skunky as hell.