Even if getbalance shows zero (as mine does), you can verify your address was sent the funds using dcrctl.exe ... --wallet listtransactions. You would probably see a single transaction, with "category": "immature" and "confirmations", 155 (in the amount of 282.63795424, just a little more than advertised). What does it take for the transaction to mature? I have no idea. But you can go to the mainnet Block Explorer and search for your airdrop address. For example, here's a transaction with a ton of airdrops. It's part of Block #1.