terminate ahead of time
По толковых словарях terminate не содержит в себе "досрочно", поэтому обстоятельство необходимо переводить отдельно.
Random House Dictionary
1. to bring to an end; put an end to: to terminate a contract.
2. to occur at or form the conclusion of: The countess's soliloquy terminates the play.
3. to bound or limit spatially; form or be situated at the extremity of.
4. to dismiss from a job; fire: to terminate employees during a recession.
5. to end, conclude, or cease.
6. (of a train, bus, or other public conveyance) to end a scheduled run at a certain place: This train terminates in New York.
7. to come to an end (often fol. by at, in, or with).
8. to issue or result (usually fol. by in).
[1580-90; v. use of late ME terminate (adj.) limited < L termin?tus, ptp. of termin?re. See TERM, -ATE1]
-Syn. 1, 2. end, finish, conclude, close, complete.
Encarta® World English Dictionary © & (P) 1999 Microsoft Corporation. All rights reserved. Developed for Microsoft by Bloomsbury Publishing Plc.:
1.intransitive and transitive verb finish: to come to an end, or bring something to an end (formal)
2.transitive verb fire somebody: to discontinue somebody’s or a group’s employment •He was terminated after 20 years on the job.
[Late 16th century. From Latin terminare, from terminus “end, boundary, limit.”]