The risk of a bitch developing mammary tumours if spayed before the first season are virtually 0%, but there is a small increase in the risk of the bitch developing lifelong incontinence.
If you spay the bitch after the 1st season the risk of her developing mammary tumours remains very small and the risk of incontinence is lower.
Our practice policy is to spay 3 months after first season, but we will do them at other times if the owner wants. The increased risk of incontinence is very small. There is not an absolutely correct answer.
If you don't intend to breed then I would advise neutering (I intend to do our puppy after her first season).
The keyhole (laparoscopic) surgery is gaining popularity. There are studies showing less pain and faster healing. Full work at 10 days may be possible if done that way. The cost is greater and the operating time can be longer. With good surgical technique and adequate analgesia the benefits are very small.
In answer to the OPs question, I would agree that 3 weeks before full work would be more reasonable.