The first Atlantic cable was landed on August 5, 1858.
[Source: Hill's Manual of Social and Business Forms, 1891, p. 349.]
For more about the telegraph's massive significance to Victorian culture, I highly recommend Tom Standage's excellent book, "The Victorian Internet".
From my latest book, Love Will Find A Wheel (Book II in the Tales of Chetzemoka, taking place in summer of 1882) :
"…Jacob suddenly realized he'd misjudged demand and made a major oversight when ordering his first shipment of stock.
How quickly can I get one here?
He was already pulling out his watch as he asked the company, "Does anyone know what time the telegraph office closes today?"
"Three p.m. on Saturdays," Felix answered with a reporter's immediate comprehension of time constraints. "And it's the one day of the week when they don't lose any time locking up."
Jacob snapped his watch closed and thrust it back into his pocket. I might —just might— make it, but I need the code list from the shop!
"Excuse me, please, I just realized I need to get there before they close."
He rushed out the door, putting on his cap in mid-stride. He grabbed his bike from where it rested against the side of the Browns' house and set off as fast as the sixty-inch wheel could take him.
At 2:59 p.m. he stood, out of breath, in the Chetzemoka telegraph office. In his hand he clutched a sheet headed "1882 Coventry Cycles Telegraph Codes." He had just sent the following message to the distributing office in England: ACT BEGIN CERTAIN ADMIRE ALLOW…"