People often talk about THE turning point in their lives, but I feel I have had several when it comes to writing.
Some will sound small, others large, but to me they are all important.
One of the first "turning points" came early on when one day the (all too common) form rejection letter for a short story arrived, but scrawled at the bottom was "Sorry, nice effort," followed by the initials of the editor. Now, that may not sound like much, but editors are very busy people and they don't take time to write on every rejection!
Not too much later I got a note that was a couple of sentences long from the same editor on another story I had submitted. Needless to say, I kept trying at that magazine! Unfortunately, I never did sell to that editor or that magazine, but it kept me going.
Then there was the day I received a letter in response to a status query I'd sent about a short story. Instead of the by then usual rejection it was a "mea culpa" for "taking so long" and the news that my story had been accepted!
The next occasion came absolutely unexpectedly. I had sent off a manuscript for a novel on a Thursday and Tuesday I got a phone call. Yes, it was an offer to publish! Talk about a major turning point! That was "Practice Makes Perfect," published by a YA imprint of Harlequin. The book has since been reissued by HSWF as "Summer Replacement."
Since then, EVERY sale has felt like a turning point. The second book felt like validation that the first book was not a fluke. I have never taken subsequent story and book sales for granted. They are all turning points, because in the world of publishing there are no guarantees.
So keep an eye out for those first, small turning points. You never know where they'll lead.