My understanding is that the processing time varies widely from person to person. I'm Nigerian Canadian. I was born in Nigeria, lived there till I was 18 and applied to the CAF after 10 years in Canada. I also spent 6 months in France on an academic exchange and visited a bunch of European countries. I'll lay out my timeline a little bit:
I applied in March 2015. My file was flagged for additional background screening because, I assume, Nigeria. And I spent 2 years there after turning 16, also I have immediate family members who currently live there (even though they are Canadian also) including my parents and a sister. I was called in for a security interview in July to review the 10 year background forms I'd filled and my file was sent to Ottawa.
After 6 months, I checked in every month or so to see if there were any updates but...nada.
In October 2016, I was asked to come back to the recruiting centre to refill and re-sign all the forms as they had expired because they were over a year old. I switched up my trades and my security requirement dropped from Top Secret to Secret so my file manger was hopeful that we'd get the clearance back within 3 months but...nada.
I continued calling once a month to check in. I'd made my October 2017 call and got no news but before the month ran out, a Captain from the recruiting centre emailed me to let me know the screening had FINALLY come back with "no security objections to enrollment" and they were going to request to go ahead with further processing. I could've screamed for joy! I was at work so I did what any respectable person would do - shut my office door, closed my blinds and did a happy dance littered with aggressive fist pumps and silent yells of "YYYEEESSSS!!!" for two minutes lol.
So all in all, the additional background check for dual citizens took 27 months for me. Since my file came back to the recruiting centre though, they've been very proactive because I've been waiting so long and my application package is competitive (according to them). They've booked me in for my interview and medical for November 23.
The ordeal has definitely taught me about patience and not to get worked up about things that are out of my hands. It was especially hard coming here and browsing through some really quick application processing time samples, but if you really want to join the CAF, go ahead and apply, then as they say here, hurry up and wait. Things could move really fast or a take a little longer than you'd like but that's alright, just continue to try to live a fulfilling life while you're waiting. Easier said than done I know, but it helps with peace of mind.