You can detect pregnancy at early as 10 days after conception via a blood test. Blood tests are much more sensitive to the levels of HCG in the blood as opposed to much higher detection thresholds in a home pregnancy test. If you have pin-pointed your ovulation day, its easy to time your bloodwork if you suspect you are pregnant.
I too am pregnant (6.5 weeks) and am curious how my band will be impacted. I have been having the opposite issue with my band where it is too tight and am scheduling a defill. I was banded in 2009 and have lost 100 lbs. I have been maintaining for over a year and havent decided yet how I feel about having my band completed defilled.
I have requested some information from my surgeon regarding prenatal nutrition as my appt with my OBGYN isnt for another few weeks.
Good luck & best wishes for a safe & healthy pregnancy!