How long after eating is still "with food"?

Factual Questions
1

Forgive me if this has already been covered.

I know that vitamin pills (and some medication, but that is far more complicated an issue, I am sure) are best taken with meals. Often, though, I forget to take them until maybe 20 minutes or so after I ate. I assume that there is still food in my stomach at that point, but is that all that matters?

How long after eating is “close enough” for this purpose?

2

Taking vitimans by themselves (no food in the stomach) could result in nausia. I think that’s the reason against it, so if true as long as you don’t get sick then I think it’s OK.

BUT

Then again maybe the food has to buffer against the chemicals in the vitiamn

BUT THEN AGAIN

I ain’t no doctor and mainly talking out of my ass here (actually I know from personal experence the nausea).