@Lisalewisgale1
A couple things that stand out:
1) Unless you own CPA has instructed you otherwise, prepaid inventory is not an expense, it's an asset and should be recorded as such.
2) Going back and adding the items to the March bill doesn't make sense as that will put the items into inventory in March as you alluded to. You want them added to inventory in July obviously. To do that, you can either receive the items with a bill or without a bill (Vendors > Receive Items and Enter Bill or Vendors > Receive Items). You "pay" the bill by moving the prepaid inventory asset to a vendor credit and applying it to the bill. To do that, create a journal entry: debit A/P for that vendor and credit the prepaid inventory asset account. That closes out the prepaid inventory asset account from March and gives you the vendor credit needed to pay the final bill from July.
