Target scheduling
Various constraints determine the suitable period for imaging an individual target, principally altitude above the horizon (which may include local obstructions) but also separation from moonlight, which floods the background, introduces gradients and reduces contrast. When imaging several targets, it may be best to divide the night and allocate time to each target only when nearest the meridian (the line from north to south through the zenith) and will be imaged through the least thickness of atmosphere.
Target scheduling software for amateur astronomers is very limited, but various websites and planetarium applications can assist with manual scheduling.
A screenshot from the Telescopius website, which whilst not a full target scheduler, offers tools for planning imaging sessions