I think I started in 1999 iirc. Anyhow it was right after when Redhat 6.1 came out.
Start here. Rute User's Tutorial and Exposition
Bookmark it. Download it. Buy it in hard copy. Whatever floats your boat.
Welcome to Linux and may the source be with you!
Now, experience freedom as in tons of choices you never knew you could make. You
are the wizard of your machine, not some idiotic program that screws up if you don't let it have it's way.
It's free as in choice and as in beer