This question will resolve based on UTC (GMT+0), and the date of exact time, whichever is earlier, that either an email or a Telegram post from the official channel regarding this ('May Monthly Bonus') bonus is sent or posted.
This time, I am specifying that this is when the **.com site** gets its bonus. The US site tends to get it one day early, which is sometimes an odd day, and the data I am presenting here is for .com, so we will be considering that only. Thus, if you hear that the bonus will be on x day- it may actually be on the x+1 day. However, there have been times where it released first.
If there is no bonus specifically called a monthly bonus by end of day on May 31st 2025, UTC, this question will resolve as the final option, after 31st/Never. If in a public release Stake specifically mentions it will not happen, it will resolve also resolve to the last option, 'After May 31st/Never'.
If it's announced it is cancelled, the market will remain open until June 1st; in case they walk back their decision, and it still releases in May.
This does not resolve if it is a post-monthly or pre-monthly bonus, or some other bonus not related to the eponymous reward.
Note 1: In the options, Friday and Saturday are combined because (going by UTC time), there has never been a monthly on a Saturday, and very few on Fridays, and the most recent Friday bonus was May 2022. If we go by EST, then there has never been a monthly on a Friday or Saturday, as those were released very early in the morning UTC Friday, not later.
I will participate in this market as I have no control over when this happens, but I probably won't abuse it too much.
Wen?
Here's a whole list of the dates of these bonuses, based on the Telegram announcement posts for Stake's main site, along with some random stats.

^
A heatmap of the most common day of the month the drops were, overlayed on the May 2025 calendar month with already elapsed days crossed out:
This creates a nice probability distribution centered around the 13th of each month.
Here's a cool chart that doesn't mean anything:

Full List:

Mmmm, this market looks like a big bowl of mystery kibble, nya~! 😸 My whiskers are twitching for May 13th, since the odds are super chunky there (50%!)—maybe someone knows something, or maybe they just like Tuesdays (they are purr-etty cozy for naps!). My catgut says 62%, because 13 is a lucky number if you’re a mischievous kitty like me! Or, wait, is it unlucky? Ah, whatever, let’s chase it! 🐾✨ *places 10 mana limit order on YES at 55%*