3 + 4

Where: When looking for an agent, their location matters a lot more than yours. Would it be nice if you live close to your agent? Yes. Is it necessary? No. Not really. In so much as your agent will need to talk to you face to face, Skype will usually do. On the other hand, they have to meet in person with editors to pitch projects to them. It's the only effective way to get your book sold. Agents in turn cluster most heavily in publishing areas. For instance, in America New York City is the single biggest. Not that there aren't other places with plenty of publishers as well. Boston, for instance. Does this mean you should only ever look for agents in New York? No, not necessarily. For instance, you might write books which are highly regional, in which case the chances are high that any interested publishers would be independent presses in the region in question. Sure, Sarah Palin's biography wound up being a big deal. Time was there was only one on the market. But usually, a book about a mostly unknown minor Alaskan politician is most likely to sell in Alaska. So to some extent you'll need to think about who might be interested in publishing a manuscript like yours and where those people might be located.

When: This may be the hardest question to answer. Well, okay. I can answer it easily. It just isn't a very good answer. Essentially, the answer is: who knows? Agencies tend to go through cycles. Times when they're actively looking for new authors, and times when they're full up and honestly couldn't rep you if they wanted to. A great deal of the time, it's the latter. And unless you're some combination of very good, very lucky, and very well connected, it's nigh impossible to get an agent to take you on when they're busy. And you really can't know whether they're busy or not unless they tell you. I suppose you could always check querytracker, but unless there is a lot of recent feedback, what it tells you about the agencies current habits is up for debate.

On a side note, I personally don't mind reading seasonal books out of season. Other readers and agents might. Considering that a book will likely spend 1-2 years with a publisher even after you've handed them the final manuscript, plus all the time spent reworking it and finding an interested publisher makes for a whole mess of a schedule. Personally, if I wrote a seasonal book, I'd probably treat it like any other book and start shopping it around soon as I finished it.