Good point
Starting your warp drive inside the solar system where there are lots of uncharted asteroids could be hazardous to your health.
But on the other hand if you wait on getting out of the solar system to start your warp drive you could be waiting 15 years to start your interstellar journey if you travel at normal impulse power.
And if you wait till you exit the Ort cloud region you will be waiting considerably longer.
I guess we need to invent the deflector shield before we start using warp drive.
Of course, planets and stars would be more like trying to push an NFL linebacker out of the way of your Cheerio...