If you used a C.A.R. purchase agreement, the agreement date is the date both parties agreed in writing. The purchase offer date is the date the offer was drafted. All dates start after "Agreement," and the default contingency period is 17 days. That is, if your used the C.A.R. form.
If you didn't use C.A.R. forms, it's whatever it says in your contract.
It doesn't cost you anything to use a buyer's agent, and if this is confusing you, I think it would be a good idea to use one for your next purchase, for your own protection. It can get complicated!
Cory La Scala, REALTOR
Lic # 01443391