They asked vets re spaying their puppy advised wait until at least three seasons.That's a new one, many vets are normally grabbing the scalpel at 6 months of age

3 months after the first season will be good enough. Certainly do not need to wait
3 seasons.
I have to say that if anyone asked me to neuter one of my dogs, just because they chose a bitch puppy, I would tell them their fortune.

I agree, it's up to the bitch owner to secure and protect their bitch, not sure about suggesting doggy day care for when in season either, be careful saxonjus sometimes we can over step the mark,

I'm sure they will take care of their own dog, and I would suggest a good groomer to at least do the first few grooms, they can learn the correct way to groom and cut from a professional or they may continue with the groomer.
I've also realised my entire male may go a little more hectic as only fence between?
Too right, glad you are prepared, he'll be wanting to go out more, may whine etc.....Male dogs can turn into houdini's, your dog may well try to get over or under the fence if so inclined, so keep a close eye, an in season bitch will excite dogs from quite a distance, on the whole bitch's are generally not too bad on their first season, but if left to have another may well be as bad as a dog and try to get to your male and anything that moves too.
Hopefully they will be savvy enough to not leave her alone at all once her season starts. But, also a good reason to spay 3 months after that first season.