In the late 90s, early 200s I used to download short stories off the net but then print them out to read. Then I got a Palm pilot and used that to read and found it quite useable. I did buy a few ebooks but not many. I think there was a site called ereader.com? I definitely remember buying a piece of software called eReader to use on my Mac and there was an associated ebook store. The fact it was my Mac puts it 2004 or later.
But I didn't really start buying many full-length novels until I got my first Kindle in 2009. It's been all "downhill" since then