WHEN in sign language
How to sign "when" in American Sign Language (ASL)?
ASL signs for WHEN
The English word "when" is used in two different ways -- one is the question as in "When will you leave?" and another is the conjunction as in "When it's my turn, my legs shake." In ASL, "when" for the conjunction is not used in English sense. It has its own grammar.
"when" as a question
Meaning: At or on which (referring to a time or circumstance).
Pronunciation (sign description): Dominant horizontal forefinger with the palm inward/down a little above the non-dominant horizontal forefinger of the similar palm orientation moves in circle clockwise around the non-moving forefinger and lands on the tip of the non-dominant forefinger.
Old variation (maybe obsolete or nearly obsolete nowadays): Two-handed horizontal "G" hands with the forefingers and thumbs facing each other apart in space move downward twice.
Related signs: WH-QUESTION.
Other WH-Questions: WHERE, WHY, WHAT, WHO, HOW, WHICH.
"when" as a conjunction
If one is signing WHEN as a conjunction in an ASL sentence, it's expressed in English gloss, not true ASL in most cases. In ASL, there are ways of using that concept without the English conjunction "when". It may be difficult for beginners; it's usually taught in the intermediate and above levels.
There is no single answer when translating different English sentences using the "when" conjunction, just like "when" can mean different in English, such as "after" or "at the same time". Here is a few examples to give you a general idea.
Non-manual signal is used. For example, for the English sentence "When it's my turn, my legs shake.", the ASL glosses are as follows: [raised eyebrows] MY-TURN [raised eyebrows], IX-me CLASSIFIER-legs-shaking.
For English conjunctions "as, when, and while" to mean "during the time that" or "at the time that", to connect two events happening at the same time, one of some possible uses in ASL are [raised eyebrows] THAT TIME or sometimes "WHILE/DURING", depending on what sentences are.
Sometimes, there is no conjunction in ASL when translating an English sentence that contains a conjunction. For example:
English: "While he was working, he often listened to radio." ASL glossed as: "IX-he WORK+++ TEND-to[ma] LISTEN-HEAR+++ RADIO." No conjunction is used.
English: "As she was leaving the court, a crowd of news reporters gathered around her. Again, the ASL sentence for this would show a scene without using a conjunction.
Can ASL conjunction "HAPPEN" be used as a "when clause"? In general, no. This tutorial on the conjunction "HAPPEN" has more explanation.