Pursuing representation can be a tricky thing. After all, not every hat fits every head.
By that I mean, you want a talent agent that services the aspect of the industry you intend to work in, such as commercial, voiceover, Theatrical (film and television), Industrial (which is another name for Corporate Spokesperson work, such as narration, tradeshow, medical, documentary, e-Learning or "explainer"), or animation, promo (such as channel-, show- and station-imaging) and so on.
Talent agents who claim, "I do everything!" much like actors who claim the same, are often too ambiguous to define their strengths. Most agents specialize just like talent do. So it stands to reason you're both more likely to succeed collectively if you're a good fit according to your mutual expertise. Ideally your (potential) agent gets the work you're most suited to excel in, first and foremost. Which is why you're better off focusing your attention on agents that suit your skill set and career aspirations when you're pursuing representation. This will actively reduce your frustration level while potentially increasing your success rate. Landing a proper agent is already a frustrating process, so no sense adding to it.
Question is: Could landing representation be seasonal? Is there a better time of year to secure a talent agent? I believe there is.
I've observed the two most successful seasons to pursue representation is during the summer months (June, July and August), and between Thanksgiving and New Year's. I surmise talent agents reassess their talent pool during these intervals, determine the type of talent their roster lacks, then interview/audition suitable talent before for the next rush of production hits. Therefore, agents may be more receptive to considering you during these (albeit slightly) less frantic periods of the year.
Of course, not all agents are created equal. Just because your friend is with 'Something Or Another' agency and got you a meeting there--doesn't mean that agency is necessarily a good fit for you too. The agent may have only met with you as a favor to your mutual friend.
Do your homework! Determine which talent agencies best suit your skills. Does the agency specializes in voiceover, Theatrical, commercial work, young adults and kids, or Spanish? If any or all of these categories apply to you, then you're well on your way. If not, there's no sense in promoting yourself to that particular agency. Narrow your list and move on. Backstage has a current list of regional and national talent agents, as does Voicebank.net, for those seeking representation solely for voiceover work.
Further determine whether the agency has funny, character types in your age range, for example, if that's in fact who you are and what you do best. As counter-intuitive as it may seem, if the agency has 3 or 4 people similar to you, then they clearly have a call for your type. Even if you may have been told in the past, "We already have your type in our talent pool." That's actually a sign you'd be in good company in that talent pool. Producers clearly turn to this agency when looking for someone like you. You want to be where there are more of your type, provided they are working!
Also, less than a fifth of all talent agencies list their submission policy on their sites. However, if they do--contact the agency to confirm this is in fact current, as it may have changed, but they simply haven't taken the time to update their site. Verify the agent's names online, and emails. However, no cold calls directly to the agents. Even if you happen to know them personally, you'll likely receive a very chilly response, and won't be making any friends. Ignoring their submission requests will only serve to frustrate yourself.
Continue promoting yourself to the talent agents until you secure representation that offers you steady auditions every week, and by that I mean an average of 3 to 8 auditions a week. In fact, I've seen talent realize the most success by following an 8-consecutive-week process I created, whether they're strictly pursuing voiceover, or on-camera, or both. It's the single most successful process to secure representation, provided your skills are sharp and your promotional materials meet or exceed industry standards.
Beyond that, knock 'em dead. The fact is the best time to pursue representation... is now! Get going!