I'll be interested to see how this turns out.
I don't suspect they will hatch early, unless your temperature is on the high side. I think day 15-18ish will give you more answers when you candle. If you see lots of clear fluid still in the pointy end of the egg, if the chick doesn't populate the entire egg, it could hatch very gooey. Usually that goo will dry super hard and brittle, so that would be my biggest concern. Watch the eyes, beak, and head especially, and get it cleaned off pronto. Your concern of possibly drowning is also valid, I think you'll know more when it gets close to hatch time.
If that time comes, and the chick still looks very small, you could consider hatching it in the upright position. Those seem to survive without drowning a little more, I believe (I've never personally hatched any upright)
Congrats to the little roo for hitting the mark! That's why its usually the other way around... bantam roosters have a harder time with their...um...um.... positioning.