If i get sperm on my hand. wash it off . but then touch a cup. and someone drinks out of that cup after maybe 20 hours. is that anything to be concerned of?

No: Concerns should only be about proper hygiene, specifically using clean cups between uses and keeping hands clean around eating and drinking, specifically during pandemic.

Doubtful : These is very very very little chance of any problem developing from what you describe. Always practice good hand washing technique.

Handwashing: I agree with other providers that this is likely a low risk scenario. However, if you use adequate handwashing technique consistently, if will help to protect your health and the health of others.