Whew, alright. I just need some advice.

I'm an 18 year old girl. At the beginning of May, I had my first ever sexual experience (which was a huge mistake) by having sex with a guy I'd just met while at a party. A condom was used, but I know he's slept around and I know that condoms aren't 100% effective, so... yeah. Worry.
Also, another dumb mistake (guessing I don't learn here) happened to me less than a week ago. I fooled around with a guy ten years my senior, who I suspect has slept with many a person before and it would not surprise me if he's done drugs also, such as shooting up which I know can cause diseases as well. We performed oral sex on each other, unprotected, but as he did not orgasm there was no semen. The BIG concern here though is that I somehow got cut externally and started to bleed, which while is a small concern in itself, worries me because it gave any sort of disease direct access into my bloodstream.
My question here is how long do I have to wait before getting tested? I know that certain STDs can show up in the test within a week, but I also know that others may not show up for months. I've looked around on a few sites but I've found so many different answers that I just do not know what to do.
Should I get tested now just to be sure, then again in a few months, or just wait a few months? I'm just so terrified, and I want this all resolved soon. Thanks for any help.
