Do you date the ds-156 when you fill it in and post it back to the London Embassy or do you date it at the interview when you sign it ?? What did other people do??

I left the date and signature blank on mine. I will take them with me to the Consulate and sign and date them there.

Thank you for your reply. Sometimes it is the little details that get you most confused. I guess they didn't object to you leaving the date blank since you have an interview now. Good luck with that !

Yes, we were specifically told in a letter that was in our packet 3 to send the ds-156 back with no signature and date but the rest filled in. It said we will be asked to swear its contents to the consular officer and then sign it in front of them.