No problem at all, set it up whenever you want. Add schools to your list, and then once you're ready you can pay for the CAS and start uploading everything (LORs, Transcripts, etc.) so you're ready to go when the time comes.
You don't need to do that since the time extends your current expiration date. If you're going to wait, you might just wait until the day after your account expires, then just pay for the ultimate package and get the full year.
Don't pay attention to people who don't know about the LSAT or law school preparation and tell you otherwise. Even if they are close to you and they really think they know what is best for you, they don't in terms of LSAT prep.
Woot representing Canada!!
If you ever want a partner to BR with, I'm down, man. I was in the same boat as you, and just taking time off from PT and just drilling and really focusing on my mistakes has helped me tremendously.