On my computer, it did not take more than 30 seconds
Hm, it depends a lot on aircraft (the Shuttle always takes a bit to load), but for a 'normal' craft under normal conditions, I have FG up and running within 15 seconds from a normal HDD (otherwise developing would be pretty painful...)
The SSD I have on my other machine is theoretically much faster but the startup time is the same - it seems in both cases the holdup is not disk I/O but things like file parsing and creating data structures in response.
Translation: On none of my systems under none of my OS I've seen a clear benefit of an SSD over a standard drive. I know others have, but for me it's always been that fast.