This is another thing… the light may not be aligned with the glideslope signal. Take this ILS 25L at KLAX for example… this is actually pretty common.
This may or may not be simulated in IF, but if you want to strictly follow procedure, if you are cleared for ILS approach follow the glideslope signal until the minimum or until transition to visual (the V on the chart above). Of course if you are cleared for visual approach, you can follow either one. I believe that this is one of the nuances that @Mustang would like to bring up in his other topic: Preferred Approach Type(s)