May Day falls on Sunday this year. The UK Bank Holiday will be marked in the UK on Monday 2 May. But we should remember that the celebrations should always take place on 1 May, regardless of what day of the week it falls on.
This was a demand of the Brussels Congress of the Second International in 1891, which stressed the holiday’s “true character as an economic demand for the eight hour day and an assertion of class struggle”.
So take tomorrow off work, by all means, but remember that today’s the day.