Payments issue during the last week of the calendar month.
There is no specific payment day for Rent Supplement claims (unlike some other SW schemes which have a specific payment day). The Community Welfare Officer will have assigned a day when the claim was first set up.
Payment for April would normally be lodged to bank accounts (I'm assuming bank lodgements) between 25th and 29th April. As Friday 22nd and Monday 25th are bank holidays, lodgements for Mon 25th will be available on Thur 21st.
If it's payment by cheque, then cheques will be issued from Thu 21st onwards, and will take 2 working days to be delivered.