When?
If we assume that the “normal” life expectancy for a full life is around 90 years, then a transition from ego-driven to soul-driven halfway through would be logical.
ReBirth
For most people, an awakening around the beginning and middle of their 40s would be appropriate. By then, you have had the opportunity to manifest yourself within society and/or learn from raising your children. You first have to build up your life, gain experience, make mistakes, if any, and then transcend these earlier experiences.
Wait Until …?
No! Don’t wait.
As soon as you notice that you are curious, follow that impulse. Get to know yourself better. Read books. Meditate. Write in a journal. Seek out nature and deepen the conversations you have.
Life will then provide clues, hints… or challenges.