When is it too late to top a clone?

I recently bought a clone from a dispensary. It was about 16 inches tall when I got it and is about 26 inches tall now. I got it about 3 weeks ago. It doesn't really have any symmetrical nodes, so I'm not really sure where I would cut the thing. I have read that uneven nodes indicate the clones were taken from an older mother plant which might explain the low end of season price.

I had a similar issue with two other clones from the same dispensary. I topped both of those with mixed results. The first seems to be generating new lateral growth while the second was taller and now seems to be growing vertically via a different half node near where I cut the main stalk.

I am a first time grower, so I'm thinking of just letting this one grow undisturbed because I've read online that topping is supposed to be done really early in the vegetative stage. This plant seems to too far along for me to feel comfortable topping it.

Perhaps next time I will try growing with seeds or simply shop for clones with more even nodes.