How quickly did the Falklands battlecruisers get underway?

How long did it take the British battlecruisers at the Falklands to raise steam and reach fighting speed?

Kent moved first while the battlecruisers raised steam. Departure around 10:00 and firing range around 13:00 are given, but an exact time to reach full speed is not established.

The British departure is placed at about 10:00 and arrival within firing range at about 13:00. Those times describe the pursuit rather than establish an exact interval for raising steam or reaching maximum speed. Kent moved out first, and the battlecruisers followed as their steam pressure increased. Sturdee ordered breakfast during the preparations. The faster British ships could close the distance without reaching top speed immediately.