Timeline in the books is bothering me!

I don't think years are mentioned in the first book. I'm reading it right now for the first time and I've gotten 3/4 through and no dates. But the fact that "puffed sleeves" are mentioned gives a hint that LM Montgomery meant for this to take place around the 1890's to early 1900's. And I think this is when the movies take place by the fashion. I'm fascinated by the story, so I've kind of looked ahead and have already read the summary for "Rilla of Ingleside." It takes place during WWI, which takes place 1914 to 1918. So I think after this book was written, it was just assumed that the first book HAD to take place in the 1870's. I can't help but feel that LM didn't originally intend for the book to take place then, but that she carelessly wrote the books with a timeline that wasn't consistent. I'm really having a hard time overlooking that she may have made a mistake.

"The hideousness of that foot will haunt my dreams forever."