The Knife-Edge
You spend a lot of time as a bootstrapped software founder on a knife-edge.
How can I afford to start a business? Will the business succeed or fail? Will anyone buy my product?
Once you overcome these questions you need to start thinking about hiring. There are a lot of great reasons to start hiring early in the success of your software business. I waited way to long with UserScape to start hiring.
This post isn't about all those reasons you've already heard about. To feed the growth, to get to the next level, to move faster, to build up sales, etc. This one is much more practical.
As you cross that line from barely making it to relatively profitable you're in an extremely dangerous position. As a solo founder or even potentially in a partnership what happens if you get sick? If you have a serious family situation? If for some reason you can't run the business for 6 months?
Not fun things to think about, but as you've probably left a good job and invested a lot of time and money to get this business going these are things you should think about. Having even just 1 great employee can make all the difference.
Even if they're not a programmer and no work gets done on the product. Someone to answer the phone, do support, help sales, and keep the lights on can make all the difference between returning to a going concern and a dead husk.