How long do you have to run the lamp for the first time? (Burn in time)

Up for continual discussion but my current personal recommendation is to orient the lamp exactly as it will be in the finished projector and burn it in initially for an absolute minimum of 2 hours. Up to overnight is fine too and won't eat up much of the total lifespan. The bulb takes many hours to reach optimal color and brightness - certainly more than 10 hours. Forever thereafter avoid short burn times - like <30 minutes. Short duty cycles shorten overall bulb life. If you leave it burning unattended be absolutely certain it's safe to do so!

I also think most of the lamps spec are taken at 100 hours.

Thanks AV! I'll try to tuck that into my long-term memory - if any is left!