Why wouldn't your DS still be on your insurance until I-Day? Or is it because these are considered "optional" immunizations rather than "required" (from the physician's standpoint)?
Our DD got two shots yesterday and will get three next month, all free at our local pharmacy through our insurance. The pharmacy then sends an electronic report to the physician's office since they're the ones who'll fill out the immunization form for the academy (we only know CGA, so maybe your immunization reporting method is different). Our doctor charges a fortune for immunizations ($800 out-of-pocket for HPV series for instance), but at the pharmacy we were charged absolutely nothing.
The local health department is another great way to go. Out here (CA) they ask if the "immunizations" are covered by your insurance, not if the "patient" is covered. Since our physicians charge so much, the health department was delighted to provide this service and we were delighted to pay as little as $6 per immunization. We went there all through our kids' childhood, but the pharmacy is working even better for us now.
I agree with Replevin and Badge - my dad told stories about how many shots the drafts would get, and we are happy that our DD won't have to enter Swab Summer feeling sore and sickly (if she's fortunate enough to be pulled off the wait list).