Based on available information (wiki and online distance converters!)
24 light-hours, 1 light-day, is 25902068371.2 (~26bn) km
22.5 light-hours is 24283189098 (~24bn) km
So Voyager has another 1618879273.2 (1.6bn-ish) km to go. Using a current speed of 17km/s (wiki says!), my maths says it will take 95228192 s, or just over 3 years, to reach the 1 light-day point.
Edit - or, what AC above said!