Can you know for sure how/when I've turned off the gas?

1. Can you know for sure how I've turned off the gas?
2. Can you know for sure when I've turned off the gas?
In #1, the words in bold is a noun clause.
In #2, the words in bold is an adverb clause.
Is my analysis correct?

I see what you're doing, yes, but it's not the clearest example, in my opinion. Here's a better one.

Let me know when you're ready.
When you're ready, let me know.

Let me know what you think.
*What you think, let me know.