I think this is one of the situations where you decide what works best for you. If you want to ask now, what's the harm? We will probably get around to the godparent-ask a few weeks/months after she arrives. It's a bit complicated for us given family dynamics, so we're in no rush.
I asked my cousin to be my little girl's godmother at my shower. She lives in Chicago, and it was the last time I'll see her until (probably) the christening. She is sooo excited! My hubs, on the other hand, doesn't plan to ask his brother to be the godfather until after the baby is born. I'm not sure why, but it's his choice.
We already asked ours, but it totally depends on your situation. We asked my sister and BIL already since they're expecting their third LO in the end of June, and my sister's schedule can be hard to work with at times. Plus, our church has set weekends that they do baptisms, so there's really only two days a month that will work.
I was planning to ask mine when they come visit us at the hospital. I was going to make a cute little card from the baby's perspective and ask them that way.
We're waiting to ask until they visit in the hospital. We're asking DH's sister to be Godmother and my brother to be Godfather. We know they'll be around right when LO is born. I'd be OK to ask now, but I kind of like the idea of waiting until they're holding LO for the first time to ask.
We don't ask our sponsors until after baby is born because its considered "bad luck" to plan the baptism before the baby is born. I'm not superstitious but a lot of the people in our church are and would talk if they heard through the grapevine that we'd already started planning. We'll ask sponsors when we go back to church after the birth (usually a week or two) and do the baptism around 6 weeks.
Re: Godparents... when to ask?
Silly husband....