Nay! You only have about half as much stem as you want. See the branch where your thumb is touching
a leaf? Follow it back and cut the main stem right below where that branch meets the main stem. The more
sets of leaves you trim off the stem the better. Also, if you are using rockwool cubes you can get away with a clone
as short-stemmed as the one you propose. I would make sure I had twice as much stem for pellets.
Go ahead and top her now. If you wait another week or so the secondary branches will be large enough to use as clones too.
That's the way I would go.
Good luck, BigSteve.