You could use a BGP import and export policy to prevent sending and recieving of routes. You could then trigger the application and removal of the policy using event scripts to achieve the delay you are after.
It's probably a little too complex for what we need it for. It's something I was hoping to invest little or no effort in to achieve the desired result - I was hoping there was a command (like "update-delay" :-)) that would be straight forward to implement but I guess not.
It's not a critical thing right now, more of a "nice to have" rather than a "need to have".