What size collar for a 9 weeks old puppy?

Getting out puppy girl tomorrow and I am going shopping later to get the last few bits.

I am clueless as to what size collar she will need... her neck looked small to me when we saw her. She seems like average puppy size if that helps.  
Would a size S (30-45 cm) collar be too big in your opinion?
I expect she will need a new collar every couple of months as she grows. But to begin with what size did you get for your pup?

Meant to write 'getting our' ooops

Difficult to know really on what size, maybe it would be better til she is with you and perhaps then you could try a few on her. Something soft though to start with so she gets used to wearing one with no irritation. 

Yes good idea I will wait until she is here.

It's not like she will be ready for walks just yet but I am so excited I feel like I need to get everything right away  

Thinking back she is 'sort of' like the size of my 6 months old cat but chunkier.

You could always go to PAH and carry her just to try some on.
Always good to get them used to a collar early on, though Vinnie doesn't wear his all the time now only when its walk time. 

Bruno is now 8 weeks old and wears the smallest size that PAH do. It fits him perfectly on the smallest setting so there's still lots of growing room!

Yes I would agree pop her along to a PAH store and try a few on, maybe an idea to have a spare too.