Time Clauses in Technical Procedures

Option B is correct. "Once" is the most precise choice here because it carries two meanings simultaneously: temporal ("at the point when") and conditional ("only after this prerequisite is met"). In deployment documentation, this dual meaning is valuable — it signals that the server will not start until migration is complete. "When" is more neutral and does not imply the prerequisite relationship as strongly. "As soon as" implies urgency or immediacy that may not be relevant. "After" is acceptable but looser — "once" is preferred in technical procedures where the completion of one phase gates the next.

Option A is correct. In time clauses, English requires the simple present (not future) even when the action refers to a future event: "until the status is 200", not "until the status will be 200". This is a key grammar rule for technical procedures — time conjunctions (until, when, once, as soon as, after) are always followed by present tense in the clause even though they describe future conditions. Option B adds "when" which is redundant and ungrammatical. Option C uses future tense incorrectly. Option D uses past tense, which would describe a historical event, not a procedure.

Option C is the best answer. "As soon as" is more precise here because it communicates immediacy — the deployment triggers the moment the merge happens, not at some unspecified future point. This matters in CI/CD documentation because it sets expectations about latency. "When" is more appropriate for general rules or recurring conditions where timing is not critical ("when the build fails, the team is notified"). However, Option A is also defensible in many contexts. "As soon as" should be reserved for time-sensitive triggers where immediacy is an explicit design property.

Option C is incorrect. The rule for time clauses in English is that you must use present tense in the subordinate clause (after "when", "once", "as soon as", "until", "after"), even if the main clause is in the future. So it must be: "When the queue is empty, the worker process exits." Writing "when the queue will be empty" is a common ESL error that can appear confusing or unprofessional in technical documentation. The other three options correctly follow this rule: "after you run", "once the certificate renews", "as soon as the tests pass".

Option C is correct. "Until" is the only connector that correctly expresses a "wait / withhold action" constraint: "do not do X until Y is complete." It defines the boundary condition that must be met before the prohibited action becomes permitted. "When" would mean "do not restart it at that precise moment" (a strange and narrow prohibition). "After" would mean "do not restart it once the requests have drained" — the opposite of the intended meaning. "As soon as" combined with "do not" creates a contradictory instruction. In runbooks, "until" is the critical connector for safe-sequencing constraints.