title: How to start clients together in SignalR
body: <p>I'm making a game. When two players accept to play together, I want to show a screen for 5 seconds telling them to get ready and start at the same time.</p>
  
  <pre><code>public class GameHub : Hub
  {
      public void AcceptRequest()
      {
          Clients.Group("players").GetReadyToPlay();
      }
  }
  </code></pre>
  
  <p>I send them a get ready signal, but I don't know what to do after that to start at the same time.</p>
  
  <p>I've two problems:</p>
  
  <ul>
  <li>I don't want to use a timer on client side to avoid a malicious
  player break the starting process. </li>
  <li>I can pass a starting time in UTC,
  but the client clock may not be set correctly. How to start exactly
  together (a few seconds is not a problem).</li>
  </ul>
  
  <p><strong>Ahh</strong></p>
  
  <p>In my above method <code>AcceptRequest</code>, I can signal them to get ready, then sleep the thread for 5 seconds, then send a start signal to clients. Is this how it should be done?</p>