Hey
MrHappy81 welcome and good growing buddy!
What D.A.A.S.69 said about the bottom of the stalk is true,as the plant grows and you tie it in other places as well the stalk will move around and get pulled,causing some stress that could be avoided.
Depending on what you want to do (
manifold,
mainline,
fluxing,
LST or
ScrOG the main/top cola should be topped differently and in different times/places.
If you are asking if she is old enough to be cut,yes she is,any photoperiod plant above the 3rd node can be cut with close to 0 stress,given that it is being taken care of correctly.
EDIT
Also MrHappy topping doesn't even anything out. If you just top and leave it you will have the same result as before only with 2 colas now competing for the top of the Feed/Light chain.
Topping requires foresight.Meaning you need a plan laid out in your head or even better on a notebook of what you are going to do with the plant to get more out of your space,your lights,your plant itself and the experience
Topping for mainlining and manifolding with the topping for scrog can be different depending on the height of your screen and don't forget,you chop all growth under some nodes in the first two methods.Fluxing is like learning to fillet a fish,surgeons accuracy needed.
Topping to get just two rather big colas and let the rest compete under LST is also a plausible option that requires less of your attention and only a few cuts or maybe even one.
Keep it Green