You can get started with the Lab at any point!
While you won't want to start working on essays until schools confirm what they are for your application cycle (usually in June/July one year prior to your planned enrollment date) as they DO change, there is lot of prep work around your overall story that you can start working on at any point (and it might be helpful to check out the advice for school essays and other things to at least start thinking about how you MIGHT approach them).
To be blunt, the SOONER you start learning what admissions committees are looking for, the sooner you can start course-correcting or bolstering your profile's weaknesses.
Put another way, we have NEVER heard someone say "I wish I would have waited and started my MBA application process later." On the contrary, the VAST majority of people underestimate what a marathon this is - not just the application process itself, but the things you need to be doing regarding career / community / test prep BEFORE you start your applications!
This article should help you get started - it's a sample of the sorts of advice we have tons of in the Lab:
Preparing To Apply To An MBA Program? Things You Should Do NOW!
Upgraded access to ApplicantLab is good for one calendar year. When your initial term expires, you'll have the option to extend your access if needed at a reduced rate - $99 for an additional 6 months, or $149 for an additional 12 months of access.
Check out this article as well (and the rest of the blog!) for some additional things to be thinking about: MBA Admissions Committees Have Needs… Do You Meet Those Needs?