Leukemia and pneumonia

I of course know that leukemia lowers your WBC and consequently your ability to fight off infections. I can't seem to find much literature on the speed at which people with leukemia can get sick and am curious. I would think it would be faster than the average population.

I know for healthy people, the common cold usually causes no problems but for those with a lowered immune system, it could cause big problems like pneumonia.

I am wondering if anyone has a clue how quickly someone with leukemia who was exposed to a virus or bacteria, would start presenting with symptoms of pneumonia? Hours or likely a few days?

Thanks!