If you don't take more than a few hours to get used to a completely different browser, editor, desktop/mobile OS, etc., you probably just didn't use all its features. I know that I still had Firefox reflexes after I had been using Chrome for a few weeks (this was a few years ago when Mozilla made some poor decisions, I tried voting with my feet).
There's a long sliding scale from "knows how to use most features of the new software" to "uses every single feature maximally and never, ever presses the wrong hotkey because an old muscle memory happened to fire". I don't think the latter is a reasonable bar to set for "get used to the new software".
Then again maybe I'm being unfair here because if I'm really honest about it, the reason I didn't switch over to Chrome was that you couldn't start an in-page text search by hitting the / key like I was used to doing in Firefox. (I've since found many other reasons to keep using Firefox but at one stage that was the sticking point...)
It took me a fortnight to move beyond other people's examples and get my first bit of nicely working verilog code written to my own spec and running on an FPGA, having never touched a hardware description language before. If it is taking you weeks to get up to speed with Firefox, what on earth are you attempting to do with it?
Regarding shortcuts, this is where using Vim emulator extensions help a lot. I just install such an extension on any new browser, then the shorcuts are more or less the same (vim keybingdings).
Step 4: Spend weeks getting used to new shortcuts, finding equivalent extensions/plugins and getting used to their dev tools.