I'm gonna go with Tiny on a few of his points...
keep'm wet when the jacket is on.. they will get hot.
Just remember this, the jackets are designed to quote keep there heads up and roll them to their backs. Most jackets don't do this. But they will give you enought time to get to them. Don't let them float around thinking the jacket will roll them to their backs. We tested this(very close to our son) it didn't roll him over and I tried alot of differant jackets(poor son..he's fine). they will hold them up.
Make sure you clean the Neo jackets everytime you get them wet, because in salt water the salt dries in them and will chafe the kiddos the next time you use it. Pull a reef shirt or rash guard t on them, helps keep them warm and cuts down on the chafing.
The 0 to 30 will be fine for her. My son wore it first and now his sister wears it and last year she was only 15 pounds at 16 months and she was great in it.. see the pic
