My Wilma had her puppies on Thursday... first puppy born at 12:35pm, next one was an hour and 1/2 later, next one was 1/2 hour later... the last one was 2 hours after the 3rd one.... (GEEZ!).... Luckily she decided to give birth during the afternoon hours!
All births are different... hopefully all yours will be born 1/2 hour in between... GOOD LUCK!!
Keep us posted.