Have not looked at any info, so this is just what I think:
I would say NO, don't
Your body should make up the VOLUME within 24 hours (cant say where I heard that)
But it can take up to a MONTH for your blood to get back to full capacity on the red corpuscle front - assuming you eat healthy & absorb your iron from food (taken with Vit C, helps absorption, NOT tea!) as your oxygen carrying red corpuscles have been depleted by 10% or more - fine for "normal" lifestyle, but maybe not 11 days before a marathon ...
can any physiologist explain it - red corpuscles made in the bone marrow aren't they?
I gave blood regularly before I had children; had a high blood count at start of first pregnancy 1984 (probably drinking more home brewed beer than tea around meal time!)
blood count 11.2 (low) at start of second pregnancy 1991 (drinking very little alchohol and probably drinking tea around meal times) prescribed medicinal iron - didn't absorb it!!! I had to have iron injections - and still didn't absorb enough
I started running when my youngest child was 5 years old - so haven't given blood for 22 yrs
I'm not trying to put anyone off, they wont take your blood anyway, if it falls below what is a very high figure (13?) - for YOUR sake, not cos they need better blood!! I've also got very common blood!!