This has been addressed a billion times both here and at t-mag, but here goes a billion and one: Take ZMA 20-40 minutes before you eat your last meal of the day.
And to round out the usual answers, there are many, including Bill Roberts, who think it’s fine to take ZMA with food, even calcium.
nutrients are normally found in food, so why would it be bad to take them with food? you could skip the calcium food to be on the safe side…just eat some eggs or something.