My situation was different from InquisitiveGuys, but for others reading the thread that might have similar concerns but different situations...
I worked in the public health field in a position in which every person before me had left after a couple years to go to med school, so I was always open with my bosses about doing post-bac.
But, during Apps I left that job and took another, in August before interview season. I told them upfront in my interviews that I would have to take time off to go to interviews. This was a job overseas and thus interviews could possibly require multiple trips of 3-7 days. They needed to fill the position and liked me, so accepted. It worked out fine.
I think whenever possible being upfront is great, but of course not always an option. In certain fields though, your bosses will be thrilled to hear about your plans to go to medical school and go far to support you.