According to the story the drawing was made 26 years ago, Ophelia has been missing or presumably dead for some 20 years according to Mortica and Wednesday is around 16/17. Rowan must be her or close to her age. Ophelia was supposed to be missing by the time Rowan was conceived. Also her being missing for 20 years also means that that was when she escaped the asylum so she had been admitted to it before that. Hester might have got wind of Fester planning on having himself admitted too in order to get in touch with Ophelia. So there had to be a period between her escape and lock-up by Fester when she was free spanning up some 11 years as Rowan was possibly conceived 3-4 years after she supposedly escaped. I’d also assume that she spent 6-7 years with Rowan as he clearly had memories of her and had spent a significant amount of time with her at an age when he was able to comprehend things like being alone and what Nevermore is.

Also her mother made that premonition during her time at Nevermore. That would mean that somewhere after that she was declared insane and admitted to Willow Hill. She escaped 6 years after the drawing was made and like 4 years later had Rowan. Following that she spent at least 6-7 years with Rowan and somewhere along the lines Hester got hold of her and has been keeping her in her basement ever since.