I started working with some clients who are targeting fall 2009 deadlines (for September 2010 matriculations) as early as this past January. I think it's very helpful to have an initial conversation with a prospective applicant as early as possible, as there are certain weaknesses in a profile that can easily be addressed - retaking the GMAT is an obvious one, or simply counterbalancing a midrange quant score with a continuing ed statistics class. This type of assessment is best done early.
For example, one of my clients had already been volunteering with a nonprofit on a long-term basis but after speaking with me, she's been able to refocus her projects there with an eye to taking on more of a leadership role, and demonstrating tangible impact on the constituents. She's now be able to use the successes she's achieved for this nonprofit in one of her essays. She wouldn't have had that sort of focused, powerful story of results to use in her essays if she hadn't started the admissions consulting process so early.
Another client had literally no volunteer work in his background at all, and based on an early conversation with me, he's now been doing a couple hours a week of service, and by the time he submits his application he'll have been doing that for 10 months. Sure, it could be seen as a 'ploy' to buff up his application, but isn't 10 months of volunteer work better than none at all? So having those initial conversations with clients often helps.
Another big advantage to starting work with us early is that EVERYONE seems to decide to use consulting services in the September/October timeframe - and consultants get really busy. If you start doing your essays now then you'll have plenty of time to work through the rounds of revision under relatively stress-free conditions (and your consultant will likely be less stressed as well!). I've had clients start from scratch with me and finish an entire application soup to nuts in about 4 weeks, but it's pretty intense to do it that way.
Remember that writing essays is a creative process -- not that you're writing fiction or poetry, but still. Writing always improves with revision, and that's true of bschool essays too. Give your essays more cycles of rework and more time to reflect on what you want to say, and definitely, you'll see waaaaaay better results (sometimes, when things get rushed as deadlines approach, quality actual DETERIORATES between versions). Most of my clients' essays go through five drafts before they're done -- for EACH essay -- so obviously getting started sooner rather than later is critical just to make sure you can get everything done on time. Plus, consultants often help clients with the big picture: school selection, defining career goals, and an overall application strategy. There are plenty of factors to review and discuss besides just essay topics.
Also, some schools have rolling admissions, which favor early submission, so it's an advantage to get things done well before the formal deadlines start in October.
To address the scenario raised by rbanks, if an applicant's life circumstances change after essays are done, such as being laid off, then yes, that would need to be addressed in the career goals essay, but any other essays that were completed might not need to be changed (i.e., your stories about past leadership success are relevant whether you're still employed by that company or not). However, I don't think that possibility takes away any of the advantages that most people get from starting the consulting process sooner.
Finally, I've also heard some people say they value having a consultant to help with essay editing and the like just because it gives them someone to be accountable to, which helps motivate them through the process. When you know that your consultant is expecting you to deliver an essay draft on a certain day, that can really help you knuckle down and get it written!
I think it's a fair question to ask, though, so thanks for posting, gob_bluth!
Lisa, Columbia MBA | Admissions Consultant | Elite GMAT Preparation and Admissions Consulting | http://www.VeritasPrep.com