Start today. 
Here is a tutorial on doing so:
Thank you
I would also begin super cropping, your plant is about to stretch and will most certainly be too big for the grow space. How long did you extend vegetative phase?
I didn’t extend it. Grobo is doing all the work.
Wow, you have a very fast grower on your hands. What day of growth are you on total? Think next time you grow this genetic an early flip to transition will be in order, assuming the pheno is showing the same super fast characteristics.
Do you have the ability to get us a brighter photo of your plant. Either by turning on a light outside the grobo or by using a flash on your camera?
Im in day 40 overall. day 2 of transitioning. I agree about an early transition the next time. I have a Grandaddy Purple in another Grobo 18 days behind this one. I will definatly keep an eye on this one.
Insane growth on the Widow, who is the breeder of the seeds you have growing? I too am growing GDP, I can tell you that you will not have the same speed of growth and will most likely end up extending late veg. in order to grow her to the appropriate height for solid yield. I foresee some troubles ahead due to the height of the Widow unfortunately, @vegetato perhaps you can shine some light on this?
I got the seeds from ILGM. This is my 1st. grow. I am going to try to bend the top down using the magnets, and cable I got for drying. Hope it helps some.
Check out this tutorial on Super Cropping, I think if you start now it will make the plant much more manageable in size.
Also, doing a significant lollipop session (trimming 20%) should slow it down a little for you as well.
I did a nice lollypop session on it. I don’t know about super cropping . I would probably break all the branches. I’ll just hope for the best.
I’d say supercrop now before it’s too late, get the canopy down beneath the 2nd fan again. A haircut probably wouldn’t hurt either.
Might also be best to just skip transition phase entirely and then extend flower phase if needed later. That’s what I’d do, as my understanding is that transition maintains higher amounts of blue (light) than flower does.
Good plan
Good job, that ought to slow her down! Did you go ahead and jump to flower as well?
Give her a few days to recover then I would remove the skinny little branches that don’t reach anywhere near the top of the canopy completely.
Not sure how to do that. In settings it says "force endgrow ". Is that it ?
No, stand by I’ll give you directions.
