agree with @guilt1905.
The sympthones of herpes usually will appear between 3-7 days from ure exposure (But the range of it, between the first day after exposure until 30 days from it).
I think u must really concern about the incubation of period for not have a false negative after take a blood test of herpes.
Hope it helps you :)
You can't have a blister this soon if it's herpes. It's probably something else but I think it's worth visiting a doctor.