Opinions on when to spay vary greatly. I suggest asking TWO vets (yes, two) what they think, and make sure that they are specific WHY. Don’t get blown off with “well it’s just better blah blah”.
Some vets have the opinion that it can shunt growth if you spay too early. The other says spaying before the cycle greatly reduces the chance of ovary cancer (which is why we spayed early) I’ve also heard that un-neutered male dogs are more likely to harass females that have been spayed after their first cycle.
Don’t take this too lightly. Get informed and make the decision that works best for you.