I'm kind of new to this, but I don't think it really matters. Your body will absorb what it needs and will excrete the rest. That's why sometimes your pee is bright yellow after taking a MVI.
The omega 3s (fish oil) I take after each meal per bottle instructions.
The only thing I think may affect the uptake is if you take whatever with a bunch of fiber. Maybe it won't get absorbed as much?
As for post-workout, unless you're taking creatine or protein supps I don't know if there is any benefit.
I take a MVI daily, sometimes I do half in the AM and the other half with dinner.