So the situation is:
My girlfriend and I were fooling around. She did oral sex to me and I ejaculated. There was sperm in her hands but she licked everything of, and we used a regular paper towel to clean her fingers almost dry. Then she began fingering herself without noticing that it was her same hand that had the sperm. Is she pregnant? Please answer I am extremely worried.
Also when is the best time to use a pregnancy test?
It's possible. If she is in her teens, she is more likely to get pregnant than if she is older. I don't think she's pregnant, but have her take a pregnancy test just in case. She should use it a day or so after she's supposed to get her period. And have her test even if she does get her period, because some women can have their period even when they are pregnant, especially in the first month.