Just to get this clear, the share drop is now after the 17th?
The SNAPSHOT of the BTS blockchain happens on a random block between midnight UTC on Sepember 1st and midnight UTC on September 16th. (The exact block can only be known based on a simple calculation that gets performed after the last block before midnight is signed on the 15th.)
The SHAREDROP happens when the Peerplays blockchain is launched, towards the end of this year. A sharedrop is when the snapshotted addresses/accounts are integrated into the Genesis block of the new Peerplays blockchain. The people who controlled the BTS held in those addresses/accounts can then use the same private keys from their BitShares accounts to unlock their new Peerplays tokens on the Peerplays blockchain.
Hope this helps to clarify your question.
UPDATE 9/17According to the calculation given in the original announcement, the snapshot will be applied to BitShares block number 9,291,600
Which was produced at 2016-09-02 16:37 (UTC)
Which means that any BTS that you had in your wallet on this date and time will be counted towards the sharedrop.