In June I received a full request for my novel. In October, the agent's assistant checked in with me, asking if my novel was still available and informing me that the agent was now
reviewing(just a guess here, but I think s/he's reading it, not writing a review) it.
In the meantime, I've finished and polished a new novel, and I'd like to start querying it. I know that I should inform the agent who has my manuscript that I'm querying a new project (1); my question is, what is the appropriate amount of time to wait before querying this new novel? (2)
My current plan (assuming I don't get a response beforehand) is to wait one more month, then send an email nudging her about the manuscript (3) she has and informing her of my new project, and begin querying the new novel shortly after. Is three months from a check-in (and seven months from a full request) ample time? (4) Or have I already waited a sufficient amount of time to do it now? (5) Several agents whom I'd like to query with the new novel have indicated they'll be closing to queries soon; I don't want to miss an opportunity to query them (especially if the agent rejects me),(6) but I also don't want to make a bad impression by nudging the agent too soon.(7)
(1) No, you shouldn't.
(2) Negative five seconds
(7) stop worrying about that
Your first obligation is to your career. Query until you have an offer for representation in hand. You are not responsible for the glacial pace of an agent's reading schedule.
It took this agent four months to start on your novel. The only thing that means is you've had four months to sit around and wait. KEEP QUERYING.
You don't have to keep her posted on this new novel either. She doesn't have first dibs on you or your work. If (when!) she gets in touch with you cause she love love loved your novel, then you can tell her the good news about Book #2.
It's not rude to do this.
It's not unprofessional to do this.
It won't leave a bad impression.
You need to keep writing and keep querying till you get an agent. Your time is NOT less valuable than the agent's. If anything it's MORE valuable. Only you can write your novels. Any one of us can sell it.
The parameters of politeness at the query stage are simple:
1. Follow the agent's guidelines
2. Follow up on a query after 30 days; a requested full after 90days OF SENDING (that's when the clock starts, NOT when the agent starts reading). Be polite in the followups.
3. If you get an offer, email any agent reading your full. (You don't need to email those rejected at the query stage or didn't answer at the query stage.)
4. Don't vent in public (twitter, facebook et al) about publishing.
That's all you have to do.
If you tippytoe around trying not to offend anyone, you'll spend too much time worrying and not enough time writing.