Don Juan is now showing on the Panama Canal schedule:
http://www.boydsteamship.com/daily_traffic_report.htm
It shows "his" arrival date scheduled for 4/15 (which you already know). Usually Boyd's PanCanal schedule is correct for arrival dates. But, it also shows his canal crossing date as 4/19. And, it will take him a full day to transit the canal. Once these ships exit the canal on the Pacific side there is a six (sometimes seven) day sailing time to SoCal. I just wanted you to know that these ships usually transit the canal before the date on the Pan Canal schedule, though, so he will probably transit before the 19th and arrive in SoCal as per the PH schedule. Every once in awhile they will run a day late into PH, though.
So once he arrives at the Panama Canal, and after he unloads at Manzanillo, he will then move back out into the outer bay to wait his turn to transit the canal. These super vessels only transit beginning in the early morning hours. Specially trained PanCanal pilots will board Don Juan and stear him through the locks. They like to watch the locks and ships carefully for damages as they pass through the lock systems (super vessels take up just about every inch of lock *******, so they begin transiting during the morning to catch as much daylight as possible. If he begins the crossing at 7 am PST, he will reach the Pacific ocean just before dinnertime. It is a 51 mile journey.
So between docking in Manzanillo and waiting his turn, he will be on the Atlantic side of the canal for probably two nights. If he transits on the 17th (or earlier) he will reach SoCal on schedule.
A few days before he reaches the PanCanal I would suggest that you try to get a free subscription to aislive.com. The free subscription is only good for two weeks, so you don't want to apply, yet. Sometimes they reply back immediately that your subscription is activated, sometimes it takes a few days, and sometimes you never get a response, so that is why I suggest trying a few days before DJ is to arrive in PanCanal. And, AIS radar only works when a ship is within 50 miles of a port, so it is not useful now. But, it is fun to watch the ship transit the canal on radar, and it gives you an idea where he is in the canal to catch him on the four web cameras.
Here is the pancanal link to the web cams:
http://www.pancanal.com/eng/photo/camera-java.html
And, I have attached a map so you understand the PanCanal system of locks. I will be following Camellia Ace and Hojin through the canal at approximately the same time as DJ.