Do you recommend patients with ESKD time their daily B complex multivitamin to after hemodialysis on hemodialysis days?

Yes. B vitamins do get removed some with dialysis but their removal is limited. Vitamin C on the other hand seems to be removed better. I don't see any harm of taking them after dialysis.

I am going to play devil's advocate here: I have never seen a water-soluble vitamin deficiency in an HD patient in 40 years, and it is not because they all take a vitamin supplement. The data is weak so they need them. I prescribe them because I'm not that confident, but this risk must be WAY overrated? Feel free to tell me otherwise.