Your welcome.
On Windows it's possible to make an application start up. I assume MAC can too. That's about using the computer. But i don't see why you would like to do that. It can be annoying in many other situations. Anything that loads will take the needed time to load no matter when it's loaded.
To me you make something difficult that are'nt. Most use a midi controller to control different kind of software. No need to load more than one need, and it could be something different each time.
A keyboard with onboard sounds don't even have to use a computer.