Before I ask my question I'll mention that my bitch is not pregnant and that I am in the process of planning her litter for a hopeful mating next December with the help and guidance of some friends in the breed. 

I know a pregnancy is on average 63 days and that, in my breed, it is common practice to try for two matings two days apart.  I wondered when do you start counting?  Is the day of the first mate day 1 or is day 1 the day after the second mate?  Or is it the day between the two matings? Also, if you have two matings at which point would you start to be concerned that the pups are overdue?  Mine is a small breed about the 8-10kg mark.

i always count the day of 1st mateing as 1st day, it just gives you a guid ,best to progesrone then when you know the right day of ovulation then 2days for eggs to rippen, you count from ovulation i think lol not from eggs rippening.

I have been counting from day of first mating although i think she ovulated on that day so it would be a further 2 days before egg was fertilised however i count my 63 days from first mating. Hopefully my small breed puppies will be with us on Sunday all going well.

I used to count from first mating but since I have been getting my bitches progesterone tested I now count from day of ovulation. :-)

From what I have read bitches consistently whelp 62 days +/- a day from ovulation.

I don't progesterone test normaly so count 63 days from first mating.

That clears that up for me nicely, thanks for all your help.