When you make a career change some days are easier than others. A lot of people doubt you and a lot of people just don't really care that much. That's not surprising - no one cares about you as much as you do.
So you need to keep your energy up, you need to surround yourself with people who understand and you need to read books that extend you knowledge in the direction you're going. You need to extend your meaning in life, and this is done by improving comprehension of your new life.
The best time is when you look back and think about your old life and realise you had no choice but to change. If you'd have stayed in the old job (or house, or relationship) you'd have lived without ever really living.
The greatest quote I've read on this subject was by the great psychologist Abraham Maslow. Note the use of the imperative:
"A musician must make music, an artist must paint, a poet must write, if he is to be ultimately happy. What a man can be, he must be."