Stupid question

I usually list eBay items for ten days starting on a Thursday evening and ending on Sunday evening, from about 6 PM onward. This is usually simple, but Thursday is the 21st and British Summer Time starts on the 31st. So anything I list on the 21st and 28th will end an hour out from the time it is listed.

Simple question - since I still want items to end about 6 PM, should I start at 5 PM or 7 PM? I'm pretty sure I should start at 5 PM, but if anyone thinks otherwise please let me know in a comment.