the Answer to that question is going to vary immensely.
What are you doing to grow 1m in NB WP a year? With that track record of success chances are you can expect much of the same successes as an indy. Unless your captive company is paying for all the marketing and you won't have the same budget to do the same as an indy.
I too am just starting my own independent agency. Just got an early release for good moral behavior as a captive (prisoner) and I am scared to death of not doing well on my own. Marketing and getting good leads is making me very nervous. But I have always been a go-getter and will give it the ol' college try.