When you're faced with sin ie an opportunity to do something you ought not to do. Now, being face to face, is the most immediate and opportuned time to call God for help - when face to face with the sin, not after engaging the sin. Truly, this is your weakest moment: face to face with sin. If you call at this time, He will not ask how you get here, He will simply empower you to avoid the sin or overcome the sin. Face to face marks the point of your weakest state. In your weakness, strength is perfected. Not after. After engaging, that power really isn't needed - forgiveness is.