There are already several threads on this subject, but here is a summary:
It takes 24-48 hours to replace the VOLUME of blood donated, but the full 100% recovery takes much longer, appx 1 month. These are my recovery times:
Steady Runs = next day onwards.
Brisk runs = one week later
Interval sessions = 1-2 weeks
Full training (long runs & intervals) = 2 weeks
Race = 2 weeks if I'm not too bothered about a good time.
Race = 4 weeks if I want a good result.
Martin.