The following sentence doesn't sound right to me, but I'm not sure whether it's actually wrong:
If neither approval nor a purchase order is required, you can quickly
create invoices at the same time AS you create records for the
vendors.
It seems to me it should say:
…you can quickly create invoices at the same time THAT you create
records for the vendors.
Best Answer
They're both fine. Both the Ngram Viewer and a general web search show that both uses are popular, with "same time as" having a slight edge. The "as" construct requires some interpolation: "at the same time as [the time]," but that's no hill for a climber.