Ask your vet..everyone of them is different..some won't do it till she's completely back to normal, (not swollen) others will do after the major part is over. So it could be 1 week or 3-4 weeks. Depending on your dog...
we have always preffered to have our bitches spayed roughly between seasons so if its a 6 month cycle this would be about 3 months after season we feel this gives time for hormone levels to be as near as normal hope this helps