E.P.
It will take about 2 - 5 days. Whenever my children have ever had strep, the first symptom that they have is stomach ache and vomiting. My children have only had strep a few times in their lives and I always dismiss their first day as a mild stomach ache or stomach flu - the second day was always worse and accompanied by lethargy, fever, the works. Just be aware if your daughter has had the "stomach flu" or has vomited, that you could have caught it from her. My son has even had strep without the severe sore throat.
Don't beat yourself up. Unfortunately with being a mom you get sick too but still have to care for others. I just walk around and disinfect handles of everything (door knobs, toilet knobs, refrigerator, faucets, etc....) for a few days. I use a spray bottle of water w/ a little bleach.
I hope you feel better very soon.