I never wrote down all my characters' exact ages. I had them set in my mind but never on paper. (Seems like an obvious thing to do first but I'm still learning). This helped a lot. I had to change some things. In my timeline, I set a character around 13 at a certain event but that couldn't be the case because I'd pictured her around 60 during another event happening at the same time.
It's also helping me determine exactly what's happened before the story. I'd written a simple scene where "Tom" was talking with "Susan". But, according to the ages of my characters and my timeline, "Susan" was gone well before the story started. It' s unlikely "Tom" would have a conversation with her in the present. Well all right, not unlikely but it's not happening in my story.
My timeline is starting to sound like math problems but it needs to be done. "Mary" is 28 at the beginning of the story and her brother "James" is 21. If "Mary" was 10 when they were taken from their parents, how old was "James"? 3. But, in my mind, I had him at a much older age. James being 3 was a complete shock! I had to take chunks out of my story!
There's still a lot to sort out but writing down the ages helped me better picture my story.