Maternity leave

I'm curious about when I should quit my job. I have to quit and reapply because I haven't been there long enough to earn maternity leave and they will not excuse my absence. I'm due June 25th and I work on a psychiatric ward for violent men. I was thinking about doing it in April. I can feel the strain on my body already from being on my feet all day and the stess isn't good either. I also feel like the bigger I get the easier target I make for someone who is having a particularly bad day on my ward. When are you guys taking leave? Am I being a weenie for considering leaving two months before I'm due?