deposit_contract_factory.sol

pragma solidity ^0.6.0;

import "../deposit_contract.sol";

contract DepositContractFactory {
  bool public deployed;
  uint public deploymentTime;
  DepositContract depositContract;

  constructor(uint _deploymentTime) public {
    deploymentTime = _deploymentTime;
  }

  function deploy() external {
    require(block.timestamp >= deploymentTime, "not yet!");
    require(!deployed, "already deployed");
    depositContract = new DepositContract();
    deployed = true;
  }
}

I reckon actually CREATE2 would be a bad idea if the salt exists in the factory because the contract could be deployed outside the factory.