Hoya kasterbergii finally bloomed with three flowers this month, but it looks like there are more buds following.  So I may see more blooms before the winter is out.  Here are the exact conditions under which it finally bloomed:

Temperature: Night time 55-60 degrees Fahrenheit (12-15 degrees Celsius) Day time High 77°F (25°C).  Lighting:  Combination T-5 Fluorescent and LED lamps.  Humidity: Day time RH 55% and Night time at 85%.