What would you define as hitting it big?
I'm doing far better than I expected, but I'm not even close to what I'd call the big leagues - Litterbox comics, Unfamiliar, and so forth.
I might not be in the Major Leagues or even the Minor Leagues, but I'm doing alright in my local club! I'm occasionally top of my genre in community comics, anyway.
My first inkling of success came a year ago, after I was over 50 pages in, when I had a comic page reach the front page of Reddit unexpectedly. I haven't repeated that event yet, but on average my comic has performed about twice as well as my expectations.
I think having realistic, low, expectations is a big help to keeping your story going. Choose stories that are similar to yours in age, reach, and genre to compare your progress with. That helped me early on.