It's a tricky one, as to both day and month.
Regarding the day, I would say xx for twenty.
The question is whether the fainter tail to the right constitutes another x, as the Ancestry transcriber appears to have concluded.
I'd say no, as the strongest part of the x is always the top, and this putative third x has next to nothing at the top. I think it's soak-through from elsewhere.
For contrast, see the date for a child named William, the second baptised in 1566. His day is definitely xxx.
Regarding the month, May is perhaps more probable. I'm not sure anyone could be certain about this month or the one for Henrye Hallyday above