Mine comes down naturally after a cycle very quickly. rbc and hematocrit both drop into normal range after i finish my cycles. But if you donate the results of your next blood test should be accurate regardless of when you take them. They are removing blood so its not like adding an ai and having to wait for things to stabalize. Assuming im reading your question correctly and your asking when to get labs again after donating blood.

I'd say anywhere after 24 hours up to about 2 weeks.

Under normal circumstances they will make you wait about 2 months between donations because it takes about that long to regenerate red blood cells.

You're not normal (I mean that in the nicest way) and your goal is to test while your numbers are down.

If your numbers come back too low, (which I doubt) you can explain it away with the blood donation.

A week or two before the test should be good.