Dressing to hide the bump?

I'm thinking ahead ladies, only 7 weeks right now.

I'll be starting a new job within the same company I currently work for in 3 weeks (only been employed there a month). I'll be 10 weeks by then. I want to wait as long as possible to tell them, so I can prove myself before I announce my pregnancy at work. I'd like to wait until 15 weeks at best.

I need some tips for outfits to hide the bump, even though I'd love to flaunt it. It is an office job, so business casual is required. This is my first pregnancy, so I'm unsure how big I'll get, and how quickly.