I would check with your vet. It probably depends on the type of stitches, how long they were in, etc. Kallie and Catcher had external metal-type stitches and they could have a bath as soon as the stitches were out.
Today is 10 days since the spay and I took their stitches out yesterday. I gave them a bath this morning . Its kinda yucky when you think of all those hands touching them so now they are fresh and clean . Its nice to see them back to their selves, I am so glad its all over and done with. Here is a picture of them after their bath drying off on the front deck in the sun