It'll be a while before we get the best photos. Right now, Dawn is in a very high orbit and will be using up all of its fuel more quickly than hoped. Any science that needs to be done at a high altitude needs to be done first, because once Dawn uses up its fuel to get to a closer orbit, it'll won't be able to come back up. Here's the schedule for working down to low orbit, from Wikipedia:

Dawn '​s mission profile calls for it to enter polar orbit around Ceres at an initial altitude of 13,500 km for a first full characterization (RC3). One RC3 orbit will take 15 days, during which Dawn will alternate taking pictures and sensor measurements and then relaying the resulting data back to Earth. Dawn will then spiral down to a survey orbit at an altitude of 4,430 km. This phase will last for 22 days, and is designed to obtain a global view of Ceres with Dawn '​s framing camera, and global maps with the visible and infrared mapping spectrometer (VIR). Dawn will then spiral down to an altitude of 1,480 km, where in August 2015 it will begin a two-month phase known as the high-altitude mapping orbit. During this phase, Dawn will continue to acquire near-global maps with the VIR and framing camera at higher resolution than in the survey phase. It will also image in stereo to resolve the surface in 3D. After spiralling down for another two months, Dawn will begin its closest orbit around Ceres in late November 2015, at a distance of about 375 km. This orbit is designed to acquire data for three months with Dawn's gamma-ray and neutron detector (GRaND) and gravity investigation.

It was initially hoped that after the primary mission, a flyby of Pallas might be possible when the asteroid crosses the ecliptic in 2018. (Because of the high inclination of the Palladian orbit, only a quick flyby would have been possible.) However, with two of Dawn's reaction wheels out of commission, the remainder of Dawn's hydrazine fuel will need to be expended to augment the remaining wheels to orient the craft in low Cererian orbit. There will be nothing left for a Palladian flyby; it won't even be possible for Dawn to leave Cererian orbit. It is predicted that Dawn will become a perpetual satellite of Ceres when the mission is over, due to its highly stable projected orbit.