Furbaby pregnancy question

Hi,

I just wanted to make sure my calculations are right.
Chelsey-my Chihuahua got pregnant on January 14th. The last day of mating was January 19th.

Do I count 64 days from the first time caught or the last time?
Thanks to anyone who can help me out.

Donna

Nice to meet u, I am newbie this forum,too. I like dogs very much .I am afraid I cant help u ,but I will bump for attention of more experienced people!