Note that there are several different ways of signing when translating from English to ASL that uses this English word. The gloss/sign FINISH as a conjunction is one of some other ways. ASL grammar is involved.
How to sign "after" in American Sign Language (ASL)?
Meaning: Later in time than; in succession to; at the close of; at a later time.
Context or usage examples: "meet me after 4:00pm".
Meaning: in the time following an event or another period of time; afterwards.
Example: "shortly after her graduation, she moved to California". ASL glossed as "/\GRADUATION CL:post-aah/\, IX1 MOVE-OUT-to CALIFORNIA".
Example: "she went out, shutting the door after her". Use classifier and grammar.
English phrase: go after. See ASL words: CHASE, FOLLOW.
English phrase: if one are after something, use TRY+GET.
CLASS/\ conj-FINISH/\, YOU CAN GIVE-ME PAPER. (You can give me your paper after the class).
Related signs: LATER.
First 100 words.
As you feel more comfortable with the first few hundreds of ASL signs, progress further with your vocabulary and learn signing more.