Contract for locking a certain amount of ether until a set date

DatePayout.sol

contract DateTime {
    /*
     *  Credit to pipermerriam for this utility contract
     *
     *  Date and Time utilities for ethereum contracts
     *
     *  address: 0x1a6184cd4c5bea62b0116de7962ee7315b7bcbce
     */
        
    function toTimestamp(uint16 year, uint8 month, uint8 day) constant returns (uint timestamp);
}

contract DatePayout {
    
    uint public payoutDate;
    address public recipient;
    
    DateTime dateTimeContract = DateTime(0x1a6184cd4c5bea62b0116de7962ee7315b7bcbce);
    
    event LogFundsReceived (address from, uint amount, uint total);
    
    //Constructor function
    function DatePayout(address _recipient, uint16 _year, uint8 _month, uint8 _day) {
        
        //Sets the address of the recipient
        recipient = _recipient;
        
        //Set the payout date in UNIX timestamp format by providing a numerical year, month, and day.
        //e.g. 2016, 8, 9 for today's date, August 9, 2016.
        payoutDate = dateTimeContract.toTimestamp(_year, _month, _day);
    }
    
    function() {
        //Return the transaction as an event to notify how much this sender has sent and the current total balance of the contract
        if (msg.value > 0)
            LogFundsReceived (msg.sender, msg.value, this.balance);
    }
    
    //This function becomes callable on/after the set payout date when the function was created
    //selfdestruct disperses the balance of this contract and sends it to recipient, and refunds any storage gas cost
    function authorizePayout() {
        if(now >= payoutDate)
            selfdestruct(recipient);
        else 
            throw;
    }
}

@D-Nice, any ideas on how can I lower gas usage of this contract?

I'm not even able to deploy it at ROPSTEN test network.