Currently, the continue reading widget shows an absolute number of hours, minutes, days, months, or years. The system default relative date behavior uses localized "Today" "Yesterday" and "The day before yesterday" (for languages that have a phrase for that, for other languages it shows the date), and then the full date for anything older.

"Because you read" currently will show Today, Yesterday, "The day before yesterday" (for languages that have a phrase for that, "2 days ago" otherwise), 3 days ago. Anything older than 3 days will show the full date - "May 12"

for "Continue reading" (and future relative dates with time) - I'd suggest showing "Just now", "1-59 minutes ago", "1-23 hours ago", then the same day/date logic described above for "Because you read"