As someone who came from Windows, and has used Linux as my primary OS for 15 years, and MacOS here and there (cos work provided laptop), I can tell you that Linux was not ready for prime time 15 years ago. Today, I feel it is, but definitely not 15 years ago.
I use Linux on the desktop since 1997, and there was no point where Windows was even slightly more attractive.
I don't know what "prime time" means here.
edit: apart from, you know. Applications and drivers for random hardware.