As the tax treatment is the same - there should not be any difference neither in quickbooks accounting nor on Schedule C reporting.
All business income and expenses would be reported the same way and should met same qualifications.
On the schedule C - in the header - you may need to mention be LLC name on the line "C" and report LLC tax ID in the box "D"
You do not need a separate schedule C for periods before and after LLC - as there is no difference in the tax structure.
You may attach a note to the schedule C with the dale LLC was created, but as the tax treatment is the same - the IRS would not question that.
There should not be any other differences.
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