What age do you let people come and see a litter for the first time? 

About 4 weeks.

Same here, first people came at 4 weeks. I really think before that they are too small, by 4 weeks their little personalities are starting to show.

4 weeks ~ at this age their little personalities are starting to show more & they're getting more active :)  I do however send photo's by email from birth to keep folks happy :D

thanks guys :-)

am knackered!

If they are local anytime, but if they have a way to come then I suggest that they pups although cute are not that interesting until 4 weeks, as they largely eat and sleep up until that age and any character traits would not be apparent to them.

i have family round from day 3 like brainless any time if local,on sunday my pupppy willbe 4 week one family in the morning one in afternoon so not to tried out mum or puppys.
but the earler better to have family and friends round to cuddle and handle the pups for socaltion too,but everyone got to take off shoes and leave them out side.and as long as they not been in contact with any other dog virus or infection,they are welcome.

I send weekly updates of the pups to prospective owners, they are invited to visit at 3-4 weeks although I limit the time they are allowed to stay to 40 minutes, going on from that though I have usually met the owners before the bitch whelps so have shown them all copies of relevant paperwork, hips, eyes, elbows etc and they have met mum and the rest of the dog family and I have chance to vet them whilst they are here.

I think you have to be aware of some owners will treat it as a day out if you don't set limits and you will end up stressed and knackered as well as your dogs.

I agree, can be very tiring. What gets me is when people cant decide what breed they want. You give your time, explain the breed to them and then they go and choose something completly different to what you were showing them !!
Going back to the original question, I usually start visits when pups are 4 weeks. They do not do all that much before that.

You give your time, explain the breed to them and then they go and choose something completly different to what you were showing them !!

Better that though than getting a pup from a breed that might not be suitable for them :)