Recently Cassandra Clare took to tumblr to answer some fan questions regarding Clockwork Princess and even City of Heavenly Fire.
If you still need to get caught up on TID, be warned, the answers are slightly spoilery.
Here's an example of one of the questions:
“Hello Cassie! c: Sorry if you get asked this a lot, but I was just wondering when Tessa, Jem and Will’s birthdays are? Because in the first chapter of Clockwork Princess (which is AMAZING! I’m so excited to read the whole book :D), Tessa says that she and Jem are young at seventeen and eighteen, so does this mean they have both had their birthdays between Clockwork Prince and Princess? Thank-you! :D — carstairsed”
Well, what it actually says is that 1) The marriage is in December 2) Tessa and Jem will be seventeen and eighteen when they get married so 3) If they are seventeen and sixteen in April of 1878, when the books start, they have their birthdays sometime between April and December.
For the complete set of Q & A visit Cassie's tumblr page.
She also informed her avid readers that the CP2 chapter titles would be released on Monday with another surprise in tow.