@fmh1 welcome to Connect. I'm glad you found the community. You may also wish to follow the Prostate Cancer group here: https://connect.mayoclinic.org/group/prostate-cancer/

I can understand you're worried about the Neulasta OnPro not working. You did the right thing by calling your doctor immediately. Your doctor doesn't sound concerned about the delay in dosage. As hard as it may be, try not to worry.

Here's what I understand about white blood cells and chemotherapy. Please keep in mind that I'm NOT a health care professional. Neulasta (pegfilgrastim) is not a chemotherapy drug. It is used to stimulate the growth of "healthy" white blood cells in the bone marrow, once chemotherapy is given. White blood cells help the body to fight infection. Chemotherapy has a cumulative effect. Friday was your first treatment, so your white blood cells may not go very low this round.

Between now and going to clinic on Monday, be sure to wash your hands frequently and avoid infection. When you get to the clinic, be sure to ask questions. When they demonstrate how to use the injector, repeat back to them what they said using your own words. I hope this helps.