Usually, they would set a deadline in 6 months for almost all the cases. (I hate to tell you this but it was the case with my application.) If you have ordered GCMS notes, the deadline is written somewhere in your 250+ pages notes (if you are under SS).The same for me
I just had a call with CIC , she informed me that Security started on 5 December and they have a deadline set to 5 May (6 months),
I don't know if SS always take 6 months or maybe even more or less , but it's confirmed , I'm in SS :/
And my ss started at the end of June and a deadline was set at the end of Dec. I regarded it as a good sign as well but it didn't turn out to be the case. I called IRCC and asked about this deadline. A representative told me that it didn't really mean anything. The deadline means an agent will review your case around the time of the deadline, but there is no certain answer regarding the time of SS.
But, luckily, according to my own experience and so many others in this thread, SS can be finalized within 6-8 months in 2019. ( 7 months for my case)
So keep waiting for the good news, be patient. Don't make it a too big deal so that it will ruin your life (easier said than done, I know).
Good luck and hope the above helps.