You have a little time. Though don't be certain of the date. It is 63 days from ovulation, not necessarily the date of the mating. Since you did not do progesterone testing to determine the ovulation date, you need to have all things ready by a week prior to the 21st.
That's best anyway as it will limit the stress.
My advice is to get a book on whelping a litter. Maybe two. You can get them from Amazon.com -- your regular bookstore really does not carry much on whelping.
The book will tell you the signs that you need to look for, signs that whelping is imminent, and signs if there are complications. Yes, you can come on here to ask questions, but at 2AM when your bitch decides it is time, going back and forth to the computer and finding an experience whelper available, might not be realistic.
The book will help you prepare -- read it prior, and then keep it on hand to refer to.
You need to keep stress to a minimum. If you have other dogs, your bitch needs a place where she is not going to be bothered by other resident dogs.
Some things you should have on hand:
Cheap digital thermometer.
A bottle of isoprople alcohol
Something to identify puppies -- I use different colored rick rack -- much better than yarn.
A heat lamp
Lots of newspapers
Towels or wash rags -- I buy the 14 or 18 packs of cheapies from WalMart, and use 3 or 4 to clean each puppy.
Some dental floss to tie off the umbilical cord if you have to cut it. If the bitch bites it, you will not need to tie it off.
A kitchen scale to weigh puppies.
A notebook to record weights twice a day
You will want a child's plastic wading pool or to build or buy a whelping box. I got a wood one on e-bay for 99$ that is functional, and has a pig rail.
Get the book, read it through twice, then come back and ask lots of questions.
Heidi Ho, Odie
Joy-Joy, Bear Cub, Hepsi-Pepsi
Cujo2, Karma Chameleon
Ramona the Pest, Kojak -- who loves you baby?
Tiny Tinnie, Susie's Uzzi, Kaiah -- The Baby Monster.