Is My Plant Ready For 12/12?

She looks healthy, you can put her in 12/12 if you're ready for that. 4 weeks veg is enough of course, but also don't know your grow conditions. What kind of light do you have, and how much grow space are you working with? I took my current grow (siggy) to 6 weeks veg before I threw them under 1000w HPS. But I was vegging with CFL's so took them a little longer to get them right for flower, at least to me. Your lady is pretty, I love any of the AK phenos.

 

 
Yes, in flower your plants will grow, it's when they do the most growing actually as your root system becomes more abundant and can start taking in massive amounts of nutrients and h2o. Assuming you give complete 12 hours of darkness. If you have light leaks, your plants will be stunted in growth and could hermie. Step up to as large as a bulb as you have the space to cool. 400w is fine, that's a good size for 1 plant and you will get some great weed off it with that. 400w also throws off a lot more heat than a 250w. Keep the temps under control, get some air circulation going.

 
AK's get huge, they are known as a heavy yielder when grown correctly. Indoors or outdoors, doesn't matter they yield well.

 

400w for 2 is fine. They would each take 1000w if you gave it to them   But 400w will keep them happy and will give you some results.
 
A zip off an AK under 400w shouldn't be a problem, LOL. If all you want is an oz, I think you will be pleasantly surprised
 
Here's an example about size difference in flower....here were mine after 6 weeks veg under CFL's:
View attachment 1494899
 
You can see where they are at now in my sig pics (or grow journal), after 5 weeks in flower under 1000w. Big difference, they are 5-6ft tall indoor. Eating up a 7x7 space and still getting big and swelling up.