Checked with my books (to get it right). After the mating it takes between 15 to 22 days before the fertilized eggs comes "down" and gets "stuck". Some bitches can get sick and / or lose their appetite during those days due to the changing hormones.
Male dogs are interested as if she was still in heat, though you know she's not.
The vulva doesn't stop being swollen.
Udder can start getting swollen, reddish week between three and five.
She can get a grey-whitish discharge after between 2½ and 3 weeks.
All these things are of course individual. To be sure :
Between week three and five a vet can carefully palpate the abdomen.
Ultrasound can be done from the end of week three, easiest to see embryos between day 28 to 35.
If it's not a planned mating, contact the vet asap.