iPhone activation date

Trying to figure out how to determine the orignal/last activation date of a seized iPhone 5S running IOS 10.0.2. I have a UFED advanced logical extraction.

I read the Blackbag blog article about that, (https://www.blackbagtech.com/blog/2013/07/31/iphone-forensics-wiped-iphone-are-you-sure/).
My problem is that, unlike what is shown in the article, the creation date of the files used as reference to determine the "post-wipe" date and time differ

sms.db 2015-10-29 90355PM
Calendar.sqlitedb 2015-10-29 62807PM
Notes.sqlite 2015-12-19 13036AM
voicemail.db 2015-10-30 14228PM
callhistory.storedata 2015-10-30 14313PM
AddressBook.sqlitedb 2015-10-29 11411PM

As can be seen, most of those dates go circle around 2015-10-29 and 2015-10-30. But what is the real activation date ? Also, do those dates indicate when the IOS was factory installed or when is was purchased and activated by the client?

Thanks for the help.