Myrna, The sizes can vary from each manufacturer or who ever is making them, they have what they call a Toddler blanket the Width from 34 to 45 inches" Length from 45 to 60 inches.
I agree they out grow the smaller ones quickly.
I am sure what ever size you decide it will be well loved and used for long time.

Thanks Pattie:

After talking to my sister and a few others I decided to go with the full size. Actually when I measured the piece it was 44x61. I talked to my sisters and a few others and they all thought that there were a lot more uses for a large blanket than a smaller one. I have enough binding to do it so why not.

I am excited about this baby. My niece has been trying for quite a while and is over the moon about it, and that is so nice to see.

Myrna, Knew you would work it out!!!

Have you ever made the Itty Bitty Dress?
You can get a PDF for newborns and large for up to a 3 toddler. Not crazy about colors they have on this one, I did a few in just white with the tiny gingham piping.

Here is a link that might be useful: Itty Bitty Dress

Myrna I am with you, I do a lot serging on fleece always round the edges.