Duuuuude. You posted a topic at midnight eastern time and waited 25 minutes before getting frustrated because no one answered your question that kind of depends on a lot of variables, like strain and phenotype if it has them, environment, style of growing (soil vs hydro), lighting.
The thing is, we can tell you 3 weeks or we can tell you 6+ weeks, you won't know for sure with your setup and genetics until you do it first hand. It would not be good if we told you 3 weeks and then it took you 6+. Or the opposite, we tell you 6+ weeks and then it only takes you 3.
Either way, you come back thinking we don't know what we're talking about...best for us to not make assumptions.
Personally in my hydro system, I can get a seed of good genetics to 12" in 3 to 4 weeks.
Anyways, most important is patience grasshopper. As a first time grower, you will find out soon that things take time...a looooot of it.
Near the end is the worst. You'll be jonesing to chop your plant up. 4+ weeks of staring at snow coated nugs, nugs that you can touch, smell, even taste, but NOT smoke can be...painful. It's a good pain though!
You'll see.
Let us know how it goes.