Scared to get teeth removed under local!!!?!

I'm getting my bottom two wisdoms out under local as it is the cheapeast. I am so SCARED! I go in Wednesday, what if the antibiotics haven't taken the infection gone by then?? When I got my upper two done 2 years ago, tried doing it under a local but had an infection and it didn't numb well, so I have to reschedule and put iv drip or whatever. However that place was nice enough to give me a payment plan. So I'm going to a different place because I need it done PRONTO and the "nice" place is all booked till March. Ugh. Help, advice PLEASE!!! Thanks!!