Her being possibly homeless has no bearing on anything.
Your chances of getting herpes from a one-time encounter are slim - possible, but slim. If the condom wasn't on correctly, you do have a chance of getting gonorrhea or chlamydia if the head of your penis wasn't covered. Tests for those two are conclusive at 7 days post exposure.
You are also at risk for syphilis. You will need a blood test for that, and it's not conclusive until 90 days, though most will show positive by 4-6 weeks. If you get a sore from syphilis, known as a chancre, you would see it between a week and 3 months.
You can test now for herpes with a type specific IgG blood test. If you test positive for hsv1, think oral hsv1 - cold sores. Even if you've never had a cold sore, it's most likely an oral infection, as 90% of those with hsv1 never get a cold sore. If you test positive for either type, it's not from this encounter, as it can take up to 4 months to show on the test, with most showing positive by 6 weeks. You wouldn't show positive until at least 2 weeks at the very earliest.
You can get herpes and syphilis when using a condom correctly, though the chances are lower, and low to start with from a 1-time encounter. Don't freak, but definitely test.
And maybe stop drinking. :)