off one’s stroke—(coll.) disconcerted or confused:
- Not that I enjoyed being shelled … but fear never paralyzed me or even pushed me off my stroke.
on the stroke—
1. (of a clock or bell) on the point of striking or ringing:
- He dressed himself hurriedly, for the dinner bell was almost on the stroke as he entered the house.
2. punctually; on time:
- We agreed to meet for lunch, and he arrived on the stroke.