Navyvet98- I think you should wait on telling them. I made that mistake with my DD, I told her that after me and her dad got married(this was Feb 2012) we would want a baby and on our wedding day, she cried and screamed for her baby bother/sister, lol. She keeps asking me when is the baby gonna come and she tells everyone that she's gonna get a brother/sister soon.
I also think that its something you should not tell kids, as they expect it to just 'happen' and that can be hurtful sometimes when they ask questions about it. Don't know if what I'm saying makes any sense, but I wish I hadn't told my DD.
Ps-we also trying for a boy, but there's really no guarantee! I've read that dtd closer to ovulation helps, as boy spermo's swim faster than girl spermo's and reach the egg quicker. Girl spermo's swim slower, but can survive longer in acidic environment.
Try googling gender swaying if you really want to try for a boy. I'm not saying it works, but no harm in trying, lol.