The center of the retrograde motion occurs at the planet's opposition which is when it is exactly opposite the Sun.  This is halfway or 6 months around the ecliptic from the Sun.  The planet's height in the sky is opposite that of the Sun's; if it occurs around the Winter Solstice when the Sun passes lowest in the sky, the retrograde will pass high in the sky at midnight, and conversely it will pass low in the sky when retrograde occurs around the Summer Solstice.  Since the planet's opposition retrograde motion is when the Earth passes closest, the planet appears at its brightest for the year.