No you can,t hurt her.
just cut em off so they r about 3 inches in length but there is no set size for them as long as you got a growing tip on top or side .
I have taken cutting as little as an inch in length when the mother is getting a little bald.
Dip em in ya rooting gel and stick em in a saturated rockwool cube in a heated propergator or on a heat mat .
If you haven,t got a heated propergator or heat mat then just use your ordinary propergator and they will root but just take a little longer.
I have had them root in winter as low as 5oc without rooting gel.
I get 95% sucsess every time.
You can,t go wrong , don,t be scared just get in there and cut em .

A good tip is cut your rockwool cube down the side to let in a little oxygen , and then you can have a peep at the stem after a week to see little white balls that are your roots starting to form.

I have just taken some cuttings so i,ll post a pic later to give you an idea .