Trek has been inconsistent to be sure, but the general accepted practice seems to be that you don't normally go to warp within a solar system. In TMP, Kirk says in a log entry that "we must now risk engaging warp drive while still within the solar system." In the DS9 episode "By Inferno's Light," Dax argues with Kira about taking the runabout to warp within a solar system. And virtually every time we see a starship enter a solar system, they immediately slow to impulse.
Now, there are exceptions of course. Heck, the Bird of Prey in TVH goes to warp within the Earth's atmosphere! But I think, in general, the "don't go to warp in a solar system unless it's really, really, really urgent" holds.