I’ve just given this a run-through here on meta and it seems to be working correctly for me?
I created a new leaderboard called ‘month’ and set the date range to be 1st June - 30th June (and limited it to @team), and it’s only picking up the cheers accumulated for that timeframe:
Though the time period picker at the top doesn’t fit so well with a date-limited leaderboard as it still tries to tell you it’s selecting a bigger date range:
I don’t think this is possible using the leaderboard page, but you can create a mini-leaderboard in Right Sidebar Blocks that can be limited to x amount of entries. The preview on theme creator is for 5, but that’s adjustable in the settings - https://discourse.theme-creator.io/theme/Discourse/right-sidebar-blocks