Problem is 17:54 is not in U.K. time zone.
The warning needs to be from when Q posted it – 20:35 EST for 24 hours.
Convert that to GMT:
'2:15 AM 17 February to 2:15 AM 18 February 2018.
And if you specify dates using the American standard like this – 2/18/18 – it will look weird to people in the UK. They would say 18/2/18 if i'm not mistaken.