Typically, I don't require everyone to post for a full round before putting the round of actions up. As in this last round, I posted everyone's movement except Kiera's because Ferrix hadn't posted by the time I got on. What I try to do to keep combat moving is post through the combat as far as the Init order allows me to go as per who has posted and who hasn't.
In terms of init and the round, Ray does have init over every PC except Yavarin. So Ray wil be moving prior to everyone except Yavarin. Of course, I always allow people to hold/ready and action as in the case of Yavarin this round. As per Fenris' stated post, I will consider this a held action until after Ray continues down the tunnel. Of course, that'll drop Yavarin in the Init Order until afte Ray. But I don't think having a held action is really what you are loking for since Cassient technically comes after Ray in the Init Order anyway.
In the end, I typically suggest a conditional post such as this for these situations: (This is only a suggestion, feel free to change it to fit the context of character/situation)
[Sblock]A. Cassient will pause for a moment to let Ray get out front a little bit and then follow Ray as quickly as he can. If Ray doesn't come upon the enemy, Cassient does a double move if necessary to remain behind Ray.
B. If Ray comes upon the adversaries and Cassient has only taken a single move action, then he will cast ______. [Remember, Shorttooth gave the party a pretty good idea that these were gnolls the party was facing]
C. Any other conditional action you can think of ... etc.[/Sblock]
Conditional actions such as that allow me to pick the one that makes the most sense using any information that comes up during the round - and keep the round going. As a DM, I really appreciate conditional actions especially when the player is hem-hawing between what to do and new information could really impact that choice. Ultimately, I'm not looking to make player's actions or movements look stupid. If new information is revealed in other characters' turns that has a significant impact upon another player's action and that player hasn't posted conditional actions, I typically stop the round in that person's Init place and give them a chance to update their action. I try to be pretty fair about it. Of course, stopping at everyone's init place can make the rounds long - which is why I love conditional actions.
Especially in circumstances like this - you know, charging down the hall after the enemy, blind because you can't see, and at any moment that drag ... I mean gnoll ... might appear out of the darkness.
See, pretty fair indeed!
[Depending on light sources - that might not be a bad idea]
