Quick question

I have 2 clones going in dwc. About 4 weeks old. 1 is growing taller, faster and skinner than other. Can I top it already. And where?

You typically can’t top clones. It’s possible and I was able to once but mine was way younger than yours.

You can absolutely top a clone. You can make another clone out of that top even, if it has enough stem.

Personally, top it when you need to, especially if you're going to give them a few weeks to veg a bit.