Allow the person that drops the portal to enter it first, delaying everyone else, so the person that dropped the portal becomes the first player to join the new instance. This would be handy for game worlds where the first player becomes a master of the instance, though also I believe this could be handy in some club instances as well.
Example: if I drop a portal, allow me to enter through it first - other people will be able to join after a short delay (like, 10 or 15 seconds) to allow me to get to the instance first.