This is a very interesting question. To be honest it depends on the risk appetite of the investor, the investment thesis, and also the market where you are executing.
When it comes down to run rate, I would probably say that things start to get really interesting when you hit $1M run rate. You are basically calculating this figure based on your revenues on the most recent quarter.
In essence, you are creating a yearly projection for potential performance. Investors are getting much pickier compared to what we used to see back in 2005. With this in mind, keeping an eye out for revenues is probably where your head needs to be in terms of metrics.
Make sure each quarter is better than the last and that you are showing an upward trend. Investors are always excited when they visualize the potential outcome towards the future and how their returns may look like down the line.