Two working days: what the reporting deadline actually says
The reporting deadline gets repeated as "within 2 working days" so often that it is worth reading what the regulation actually says. Regulation 4(8) sets the deadline at "the end of the second working day after the day on which the load of controlled waste or hazardous controlled waste is received".
The day the vehicle arrives does not count. A car that comes in on Monday is due by the end of Wednesday. One that comes in on Friday is due by the end of Tuesday, because Saturday and Sunday are not working days. The regulations define a working day as any day that is not a Saturday, a Sunday, Christmas Day, Good Friday or a bank holiday in England.
Corrections have their own clock
A different deadline that gets muddled with the first: fixing an error in a record you already submitted. Regulation 7(2) requires the correct information "as soon as reasonably practicable and, in any event, within one month of the date on which the operator of a permitted facility becomes aware of the error". One month from becoming aware, not two days.
The practical read
None of this changes the sensible habit: report the day the vehicle comes in and the deadlines never matter. But if a bank holiday weekend or a broken tablet puts you behind, knowing the real line matters. The duty is triggered by receiving the waste, not by treating it, so the report never waits for depollution either.