Technically speaking, something like 98% of all BA surgeries are more or less problem free from a medical standpoint, with maybe 2% resulting in some sort of complication. Of that 2%, 80% of the complications are easily correctable. Also the likelihood of complications when the BA surgery is done in a hospital O.R. is lower than if done in a doctor's private office surgery. As someone else posted, the odds of dying or of developing any sort of serious and permanent medical problems from a BA surgery are probably much more remote than the odds of getting hit by a car when crossing the street !
The first BA surgery may be a bit scary because of your fear of the unknown more than anything else. Trust me, other than enduring some post-op pain, it's no big deal. Remember that a BA surgery only involves skin and muscle, and does NOT involve opening up your chest/rib cage/abdomen the way most "conventional" surgeries would.
If/when you go back for bigger implants in the future, you'll probably remember your first surgery and laugh at yourself for worrying so much !
Actually, the biggest risk you probably will face comes from the fact that you have three young [censored] ! For your first week post-op you're going to have to fight the temptation to grab them, you're going to have to keep them from bumping into your new boobs, you're going to have to avoid reaching and lifting, etc. A significant number of BA complications are actually caused by the patients themselves "overdoing it" between the time of their surgery and the time that the stitches are removed, causing stitches to pop, incisions to reopen, implants to shift position etc. Make sure you have plenty of help lined up in the kid department !