Anytime, mate... that's a bit of a place where you can be caught out if you're not careful, though for most end-users it won't really make much difference. I doubt my wife knows what a file system is, and she uses my Mint laptop without hassles.Update:
Thanks to Newby_Investor for pointing out that the file system is different between Windows and Linux.
If you're happy with Mint, there's no real reason (other than just for a learning curve) to install Debian. I've done all the more DIY-style distros back in the day, ones like Mint have matured to the point where you can just install it and do your work (or leisure or whatever you're going to do).I am happily enjoying Mint at the moment. After getting used to the OS for almost a month, I am going to back up my data and install a more complete Debian package.
I will not be using a Windows system at home again and the learning experience is actually fun.
A few months ago, forget how long exactly, they did a complete re-design. It got a lot faster overnight. Still hogs a lot of memory, but I guess I just open too many tabs...Edit: when did Firefox get so good?