So here are my questions and my opinion
What kind of lights are you using?
Do you have a timer?
do you have a bigger planter?
What kind of space are you growing in?
Opinion: It looks to be about 3 to 4 weeks old, not having been topped, it will get quite a bit taller during flowering, remember - plants can double even TRIPPLE in size once flowering is completed. So if your plant is 12" tall, it's gonna be 36" tall when it's done (or three feet tall). Ways to avoid tall, is by topping to make it go wide. I personally try to veg for 4 to 5 weeks before sexxing and flowering. your plant looks healthy dispite the stretch (which wasn't severe) so you're doing something right. I suggest repotting it into a 5 gallon bucket, and keeping lights as close to it as possible...you need around 5500 lumens per square foot, to ensure good internodenal spacing and keep it nice and dense. anything else? i forget....lol good luck! I'm sure i'll have more advice once i get more info