Which date can I use in citizenship application form?

[Mattcorp99]

My hearing was at 1 oct 2017 and I got the positive decision during the hearing.
Notice of decision letter received on 23 Oct 2017.
My notice of decision letter says the claim were heard on 1 oct 2017
Can you help me which date can I use in citizenship application form.

 

[Mattcorp99]

Please somebody take serious my problem. I need asap help
Thank you

 

[Das67]

I used the date my NOD letter was signed at least if IRCC has any question I can prove it by showing my NOD letter.

 

[Mattcorp99]

thank you