As long as there wasn't too much fluid in the egg (and this goes for other positions not just a baby in the small end) it should be able to get air with an external pip.
Since it's in the small end its internal pip and external pip are one and the same so expect for a longer wait from external pip to hatch than in eggs that pip on the correct end. I think up to 48 hours would be in the normal range. Usually they can turn to zip just fine in this position but I'd watch it to make sure it doesn't struggle with the zip (when mine have trouble zipping they widen that external pip, usually peep a lot and will continually strike out with their little beaks but don't get anywhere). Since it just pipped recently you won't have to worry about zipping for quite a while though and it's likely it won't have a problem.
Good luck, I hope everything goes smoothly for the little one, and congratulations on the first pip!