Welcome to the Query First Theory.
I know I'm not the first person to say it, but there's a benefit to writing the query before you write the novel. Especially for pantsers like me.
KEEPING THE STORY ON TRACK
Many of us pantser-types resist having an outline or a synopsis before-hand because we feel that the level of detail will sap out all the creative juices. A query, on the other hand, is not really about details. It's more about generating interest in the concept behind the story.
By writing a query first, you can check back in periodically on ensure that the manuscript is staying in tune with the big picture. It helps keep your story about dealing with grief not turn into a story about auditioning for a reality tv show. (Fellow pantsers, you know this happens.)
CAPTURING THE VOICE
Writing your query before the first draft can be a way to discover voice, especially in YA. Consider this example from the back cover of Twilight:
About three things I was absolutely positive.
First, Edward was a vampire.
Second, there was part of him — and I didn’t know how potent that part might be — that thirsted for my blood.
And third, I was unconditionally and irrevocably in love with him.
I think this captures Bella's voice perfectly. It also fulfills the first requirement of directing the story- every part of the first book of the Twilight saga is concerned with the fact that Edward is a vampire, that he must resist the urge to have Bella a la Cullen, and that Bella is totally hooked.
Also, consider this excerpt from Karsten Knight's query for WILDEFIRE:
Ashline Wilde never received an instruction manual on how to be a 16-year-old Polynesian volcano goddess. If she had, it might have contained helpful warnings such as:
Dreaming about your (thankfully) mortal boyfriend may cause your bed to spontaneously combust
Oven mitts should be worn at all times during heavy make-out sessions
Wildefire hasn't been released yet, but the voice- even moreso than the story- makes it a must-read for me.
TIME IS ON YOUR SIDE
Much of the query-writing pressure is actually time pressure. You write a book, you want to get it out there, but you have to stop and boil down it's essence in a witty way. ARGH!
Writing a query beforehand means you can come back to it periodically through the whole process- first drafting, second-drafting, critiquing, editing, etc. It means you can tweak the query if you need to change your story. You've got months to find the perfect words to show your story. And when your manuscript is ready to go, your query's already chomping at the bit.
Any other reasons to write the query first?