I would say "get ready for: very long days, tons of stress, arguments with co-founders, doing lots of things I have never done before, continuous learning, being humble with customers, accepting failure and moving on, continuous re-planning, learning to do more with less, accepting that luck is a factor--but being in the right place can affect your luck, be bold, and be ready to grow as a person."
I was born & raised to be an entrepreneur so it was no leap to know that I would do it.
>very long days,
etc. has always been known to come with the territory.
I probably only became conscious of it as about a 12-year old, but there is a piece of advice I was well aware of by then.
Of course, I wanted to take initiative but I was too young.
Regardless, there is advice I always heed, and I was cognizant that my actions did not yet reflect my desires.
Anyway, I was doing pretty good in my father's company at the time.
Later, after college it was truly wisest to work toward employment with a multinational outfit, to become established in an industry before going out on my own.
I witnessed all kinds of amazing opportunities pass me by for a number of years, I wanted to take initiative but it didn't bother me because I just couldn't afford to open up shop yet.
Once I did start my company, more opportunities and more difficulties did arise than I had anticipated, but I wouldn't have done it any other way.
Now with 20/20 hindsight the one piece of advice that has always been in view and seems to stand the test of time.
This isn't just how I felt 6 months to a year before I left my employer, this is how I felt for decades before starting my company:
Start Sooner.
That's why I did manage to start it as soon as I could, and it was a tremendous advantage.