Home proposal ideas?

I ve been trying to come up with a good home proposal idea. We have been together for a few years, and have a 15 month old daughter. I m committed to proposing on a particular date, as that date would be the anniversary of the date we found out she was pregnant. I ve purchased the ring, and bought a onesie that states "mommy will you marry my daddy?." I ve heard from her sister that my girlfriend believes I purchased a ring because we received recent mail from the jewelry store. Given the circumstances, what s more important, something romantic or completely surprising? How important is it for a woman to "look good" when being proposed to? What are some general ideas I could consider?