I took my bitch to be palpated today, on day 33, vet said she could feel one but not the string, but could be more. both other times i`ve had litters im sure i took her earlier (different bitch) anyone had any exprience of this?

That would be too late to palpate reliably as the units can't be distinguished readily due to fluid build up in the uterine horns.

The time to do it is 23 to 28 days.  After 28 days you would need to scan. 

After 6 weeks then the pups would be palpable again.

Thats what i thought, was pretty sure i was right but needed someone elses opinion, she was booked in earlier but the vet changed the appointment to later in the week! when i asked if it would be to late they said it would be fine, maybe they didnt want to lose the consulation fee!