In my own case, my status changed to "decision made" in 2nd half of April; don't know the exact date. I was told this when I called up IRCC on 28th April. In the new status tracker system, I don't see any "decision made", so I guess they have removed that concept for the applicant; might still be present on their own end.
Other than this it's a new system, and I only know what I read online here:
https://www.cic.gc.ca/english/helpcentre/answer.asp?qnum=1465&top=5
Of the 6 sections, 5 are "completed" for me, and the 'citizenship ceremony' says "not started". Also the overall status on the top says "in progress".