Entering the field is not enough to meet the Timed out requirement. The relevant question is readiness to receive the next ball within the applicable period, not merely arrival near the crease.
What the standard Law requires
Under Law 40.1.1, after a wicket falls or a batter retires, the incoming batter must be ready to receive the ball, or the other batter must be ready to receive the next ball, within three minutes unless Time has been called. The relevant wording and exceptions should be checked in the MCC law on Timed out.
Arrival is evidence of progress, not necessarily readiness. Check the batter’s preparedness and the applicable playing conditions.
Hypothetical standard-Law example
Hypothetical facts: A wicket falls. No Time call is made. The incoming batter enters the field before the three-minute period ends, but remains unprepared and is not ready to receive by the deadline. The other batter is also not ready to receive the next ball.
Outcome: Entering before the period ends is insufficient. On these stated facts, the incoming batter can be given Timed out because neither batter met the readiness requirement by the deadline. This conclusion follows from the assumed facts, not from any real match decision.
Contrast and competition limits
For contrast, if the incoming batter enters during the permitted period and is ready to receive before that period expires, merely having taken time to walk in does not create a Timed out dismissal. Similarly, the incoming batter need not be the only relevant person: the other batter being ready to receive the next ball can satisfy the stated alternative.
The three-minute period used above reflects the standard-law example used here. A tournament’s playing conditions may alter the period or procedure, so it must be checked rather than assumed for every format. This explanation addresses readiness under the stated hypothetical facts, not a prediction about a real match.