St. Ignatius Loyola suggested the best times to consider making vocational change:
1) When our will is moved to a point where no hesitation is possible.
2) When we find light and information through reflection on our experiences of desolation (darkness, turmoil, sloth, tepidness, etc.) and consolation (movements tending towards faith, hope, love, peace, etc.)
3) In a period of calm, when the soul is not agitated by diverse spirits and exercises its natural faculties freely and tranquilly.
He recommended imagining yourself at your point of death, then asking what path would you wish you had taken. Also, how would you advise another honest seeker in the same situation if they were seeking your counsel?