The problem with discussing success in self-publishing is that everyone is going to have a different definition of success for themselves.
Some people will consider a successful launch as success, while others will hold themselves to a dollar amount or a number of sales within a time frame before they consider their book a success.
For example, I have 4 tiers that I feel my work will fall into once I get it published and into the public.
Tier 1: Raging Success. Each book will not only recover it's cost, but will fund above and beyond the cost of the next work (editing, advertising and cover work).
Tier 2: Success. Each book will recover its own cost but will also make between 25-75% of its cost in profit, thus helping to fund the next book.
Tier 3: Mediocre. Each book will recover it's own cost and up to 25% extra.
Tier 4: Not successful. The book, at best, recovers its cost or not at all.
I plan on giving my books a 9 month window before I make a decision on the results. That will give me enough time to really work on the advertising and get the book out there as well as work on the next one and make adjustments based on feedback and sales results.
So what do you consider success? Just getting published? A certain dollar amount or a certain number of sales within a given time frame?