donating blood & exercise?

I did c25k this winter & have been very dedicated at continuing to run faithfully three days a week and have signed up for my first 5k on June 9th. My church is having a blood drive on Thursday and I want to donate. Usually Thursday is a run day, should I alter my schedule this week or will I be ok if I just make sure I am well hydrated? I run in the early AM, so run would be several hours before I donate.