personaly if you dont want to breed spaying is the best thing, but its up to you.
for me all my girls were done at 6 months old well 5 1/2 but that was advised by our vet, aparently it is ment to prevent or reduce the risc of mamary cancer, which is what both my mums cockers had when they were older. they were spayed after their first season. but ultimitly itsd up to the vet, some vert refuse to do it till the dog is 18 months old. so best talking to your vet and seeing what they say when she gets her next jag.