Hi,
As a former admissions officer and former recruiter for McKinsey, I can tell you that more work experience is indeed better. Not only will more time at McKinsey give you a greater depth and breadth of experience, it will also benefit you in terms of matching your bschool applicant peers. A large number of consultants apply to bschools each year, and if you apply with just a few months experience under your belt you'll find it difficult to compete with those with 2-4 years experience.
Additionally, the more time you spend working prior to bschool the more you will likely get out of the bschool experience. Also, from a hiring standpoint, recruiters would likely be more interested in candidates with more experience prior to bschool than just a few months or a year.
Try to get staffed on a variety of projects in different industries and countries. McKinsey has amazing opportunities for BA's - take full advantage of them.
Best,
Stacey
