Yes.. Send it because previous year I received my offer letter 4 days after the expiry of acceptance date by establishment division through post. But, with grace of Allah almighty, I had sent my acceptance in reference to the press release earlier.
For guidance of offer letter etc. to to this link given below:
http://www.cssforum.com.pk/css-cadre...-division.html
Take care.. Welcome & BestEST of luck to all new probationary officers of 39th CTP.