See this help file http://support.chess.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=31
Basically, every member has a certain amount of vacation time-a time during which you can pause all of your games (so you won't lose on time just because you're spending a week hiking).
Now, every member gets 7 days on his account when he signs up, and two more days every month. Premium members get more vacation time than free members.
When you put yourself on vacation, your time counts down.
So your vacation time is: 7 + months you've been here * 2 - vacation time used (in days)
Now, I presume you're talking about your game with jimthemagic. He has an entire month of vaction time left, but he might be back sooner.
Being new to this site, I don't understand this "vacation" stuff. How long can your opponent be on vacation?