Yes of course there is some risks but you cannot succeed if you don't try. I just put some targets according to the money I've got in the bank. It was OK because we (family) have had enough money for more than one year without income. When my first app was mentioned in the NYT, I realized that there was a market and it was possible to do a sustainable living. I also realized that promotions was the key once you've got a good product - OK everybody know that but when you are an indie with a software engineer background it's not easy to do it because you are reluctant to do it.

biggest challenge : designing innovative apps and doing the promotions (then artwork)

my family was a great help to stay motivated. My most important issue was money and being able to feed my family, but My wife told me that it was better if we didn't have a lot of income and I was happy with my jobs and stayed at home with her and the kids. She was so right. Doing something that you enjoy (and of course where there is some money) is the key to stay motivated (for me and I think for a lot of people).

what kind of promotions did you do ?

please check the post. But actually everything is good to promote your app, you have to try and see the result. The difficulty in promotion is that most of the times difficult to evaluate to ROI and it is a kind of weird thing for software engineer - you don't know if it works or not (except if you've got a mention in a major blog/newspaper). But mentions in major blogs or newspaper don't appear by magic, you have to make some noise about your product.

So You just want that your app is visible to everybody. If, by magic, everybody was aware of my apps I would sell 100,000 units in one day I think !

You mention that Children's Technology Review gave you an award. Did you contact them and pitch the app or did they find the app on their own?

I just sent them a code to review the app as I did with a lot of blogs or children's technology specialist

If things had not worked out as well as they did, what was the backup plan?

go back to work as an employee or contractor !

I'd imagine 100's of sales / day, and all that money keeps your motivation levels sufficiently high.

yes once you reach a threshold it's more easy to get motivated :-) But this is the start that is the most difficult, of course

How long after release did it take you to reach those 100-200-500 sales per day? I've had some moderate success with an Android app, but nowhere near 200k. :)

Let's say that for me it was profitable last January and I began to work on iOS in March 2010. Of course it really depends on what you need. You can check the figures in the post to see details.