How early is too early?

It looks like we had a similar question here. You can either deliver them a week early or forward-date the thread by up to seven days.

Premature birth is one week max...

Birth threads can officially be forward dated (pups born on original due date, but thread is posted earlier) by a maximum of 7 days.

For the pups, have them add a link to the birth thread in their prompts so we can see that it's valid and there should be no issues with their acceptance!