The phrase "alarmingly soon" is correct and usable in written English.
It can be used to describe something that happens unexpectedly or too quickly, often with a sense of concern or urgency.
Example: "The deadline for the project is alarmingly soon, and we need to work faster to meet it."
Alternatives: "worryingly soon" or "frighteningly soon".
Given the rocky NAFTA talks happening this week, though, worse could come alarmingly soon.
The two most recent fatalities have seen the tally rise to six deaths since 2011, and have put fabric's drug policy under investigation again, alarmingly soon after their last narrow escape.
Even more alarmingly, we are soon asked to don eye masks and -- yikes!
The descent was rapid, at about 3,000ft a minute, but not alarmingly so, and it is not clear how soon the captain and flight crew – let alone the passengers – would have noticed that anything was amiss.
They had resumed on 46 for two, but soon descended alarmingly to 59 for six – with five successive batsmen, including Ian Bell the previous evening, making eight runs between them.
In my home province, for example, it will soon be alarmingly difficult to access caregivers who will provide abortions.
Life is nasty, brutish and soon to be alarmingly different.
She wanted to live up to Tony's expectations — in this she resembles many le Carré characters, who are eager to please and who find it alarmingly easy to lie — and she soon finds herself with an entry-level job at the intelligence service.
The first shot had him looking alarmingly young, boyish and eager, but he soon transcended that.
Pompey had soon become restive toward his alarmingly successful ally Caesar, as had Crassus toward his old enemy Pompey.
Alarmingly, the State Department declined to include any analysis from the soon to be completed USFWS biological opinion regarding the Keystone XL Pipeline.
