It’s almost certain FBI had the dossier before McCain ‘delivered’ it:
https://www.theguardian.com/us-news/2017/jan/11/trump-russia-report-opposition-research-john-mccain
...By July, the counter-intelligence contractor...delivered his reports...[and] a set to former colleagues in the FBI...
...In mid-November, the documents took another route into Washington... McCain arranged a one-on-one meeting with Comey, with no aides present, and handed them over...
Thanks for your input.
It does appear that McCain was late to the game with regard to the delivery of the Trump Dossier to the the Obama Administration agencies.
I know it’s stupid to suggest this...but could there be different versions of the dossier, and Fusion sold it at different times?