let me know when do you want me to sign vs let me know when should I sign

Some examples from the web:

• Let me know when you want me.
• So just let me know when you want me to head to the kissing bridge.
• So when do you want me back tomorrow?
• When do you want me back?
• So, when do you want me out there facing the reporters?
• When do you want me back?
• Where and when do you want me to start?
• Then when do you want me to be frightened till?
• When do you want me to come back in?
• When do you want me to go?
• When do you want me to stop, then?
• When do you want me to go?
• When do you want me to tell the old man?
• Let me know when you want to get started on that bed.
• Let me know when you want to have a real conversation.
• Let me know when you want more.
• Let me know when you want it lifted. Yes, sir.
• Just let me know when you want to take the time.
• So when do you want your poker lessons?
• When do you want us to start building?

Some examples from the web:

• When Tyler gets here, let him know she'll sign for Marks.
• Let me know when we're talking.
• Let me know when everything's ready.
• Let me know when you narrow it down.
• Ernie? Let me know when you get the spotlights finished.
• Let me know when he's gone.
• Please let me know when I can return the favor.
• Let me know when my ambulance gets here.
• Let me know when I can have my tissue.
• Let me know when you do.
• Let me know when the bones are clean, Mr. Vaziri.
• Okay. Let me know when the bones are clean, Mr. Vaziri.
• Let me know when dinner's ready.
• Let me know when your cookbook comes out.
• Let me know when you've secured the crime scene.
• Let me know when you finish that reconstruction, Ms. Wick.
• Let me know when you find her.
• Let me know when you find something that actually helps Tommy.
• Let me know when there's a good day.
• Let me know when there's a good day.