Unfortunatly, you cant start the policy before you get your pup...and then once you do get him or her, and you do start it...it doesnt become effective for like 10 days or so.
So for Piper's first appointment (which was like 3 days after we got her)...we just had to eat the cost at the vet without getting reimbersed by VPI. It ended up being like $80.00 or so...but we got a check up, 2 shots, worm test, frontline and interceptor.
You could always make your first trip to the vet a bit cheaper but just getting her a check up when you first get her (which is around $30 or so) ..and then take her back a few days later (after your plan goes into effect) for the shots and the flea/tick and heartworm medicine.
Your breeder should be taking your pup for a final vet visit right before they turn the pup over to you anyway...
Hope this helps.