How to sort contacts by creation date or modification date in iOS Contacts or OS X Contacts 7.x?
After digging a little bit in Contacts' DB here is what I found. 

As already said by @grgarside, the DB is in 

~/Library/Application\ Support/Address\ Book/Sources/&lt;source-ID&gt;/AddressBook-v22.abcddb


Where &lt;source-ID&gt; is most likely the most recent modified directory. 

AddressBook-v22.abcddb is a SQLite DB file with 24 tables (in my case). The most important one is ZABCDRECORD which holds (among others) the firstname, lastname and the creation date of the contact (but also modification etc). 

The 2 interesting columns in your case are : 


ZCREATIONDATE
ZMODIFICATIONDATE


As I found out recently, the base date for these 2 columns is 01-01-2001. 
The columns ZMODIFICATIONDATEYEARLESS and ZCREATIONDATEYEARLESS  use the 1st January of creation year as the base date. 

Using sqlite you can sort it like that : 

sqlite3 AddressBook-v22.abcddb "select ZFirstName, ZLastName from ZABCDRECORD order by ZMODIFICATIONDATE"

It will output FirstName/LastName sorted by modification date.