Use the Wallet Chain Activity endpoint with the contract address. In the requested chain's active_chains entry, first_transaction contains the first observed transaction hash, block number, and timestamp when available.
Replace {address} in GET /wallets/{address}/chains and authenticate with your Moralis API key. You can pass chains to limit the networks queried. The first observed transaction is an activity signal; it is not necessarily the contract deployment transaction or the date the address was created. Check the deployment transaction separately when you need deployment time.