Just read that many strains will require 9 weeks flowering. So after 2-3 months vegging, you then flower for another 2-3 months. Yield is 2 ounces plus. That is almost half a year for about two ounces, seems not right... If you use an ounce a month, it would be very hard to supply yourself?
There are a ton of factors. In the article you read, I am sure that is true for that growing type with those lights and fertilizing schedule. What your stating is seedling growing. Initial seedling stage can take a few weeks, then flowering is usually anytime after 2-6 weeks depending on how large you want them to get. Then flowering can take anywhere from 4 weeks to 12 weeks depending upon the strain and its habitat. Having a mother plant, going from clones instead of seedling. Say you go the clone route, you buy or acquire a clone, plant it and give it 3 weeks to settle in and grow some before you flower, then you have 4-10 weeks on normal for flowering. It would be just under 3 months per harvest. Now lets say you have a mother plant your taking clones off every 2 weeks, in 3 months you will have a harvest from 1 plant and then every 2 weeks from that point on you will be getting another crop. So initial startup may be slow but you can speed things up down the road. Happy Growing!
You're also talking about a single plant and final yield isn't being mentioned. Growing one plant is certainly not the most cost effective way to go. I'll have four plants under a 400w, each with three stalks topped. With a high yielding strain, this makes a pound trimmed & dry at harvest. And keep in mind that if you put the effort into it and get ahold of quality genetics, most of that pound would be stuff that gets seasoned smokers stoned in two hits. You also don't seem to be considering the fact that with separate veg & flowering areas, you only have to wait through both vegging & flowering once, if you keep growing. Plants for the next grow can then be vegged while the previous run is flowering and you only have to wait through the flowering cycle. A vegging area can be smaller than 2' tall, so doesn't need alot of space.