Hey Tony,
I am going to make a few assumptions here and if I am wrong please feel free to correct me and set me straight as to what the facts are.
I am assuming your not going to be switching out to LEDs or HID lights for when you flip here to flower.
I am also assuming your grow area will not get larger when you decide to flip her.
With the assumptions it is safe to say your not going to be verging your girl to 30 inches and growing a big plant.
Here is a very simple way to decide when you have to flip her. With your light as high as it will go in your grow area and your container as low as it can go, measure from the top of the pot to the light the subtract 3 inches since you are using CFLs. This number is the maximum grow area you have to work with. Write that down For this example we will say it is 40 inches after we subtracted the 3 inches for spacing of the light.
Now your plant will continue to grow after you flip her and the general rule of thumb is a multiplier of
1 1/2 times for pure Indica plants
2 times for Hybrid plants
2 1/2 times for pure Sativa
With out going back and rereading your posts I am assuming what you have is a Hybrid since 100% pure plants are not all that common. so lets do some math.
If you grow your plant 20 inches tall, thats from the top of your pot to the highest point of the plant and flip her she will be roughly
20 + (2x20) = 20 +40 = 60 inches. Nope thats to tall for a 40 inch grow area
Now this time lets work backwards so we can get the right size for this without just guessing each time.
H+(2xH) = 40 inches (where H = height of plant in inches)
3H=40 inches
40/3 = H
A=13 1/4 inches is when you will need to flip for a 40 inch grow area.
Now go measure your actual grow area using your light and pot and plug those numbers into the equation. That is the tallest you should grow your plant.
Hope this helps Tony.
Now you can always flip her anytime she is shorter then that height, but that is the tallest you want to grow her. Now keep in mind there are tricks like LST to help keep your plant short even as she grows to increase your yield.