Have tried the variables as suggested. I ended up with {year4}\{month0}\{day0} on a Windows machine (before I try the Mac). Interestingly, even though I definitely typed a / this was translated to a \ in the ingest box.
I needed {day0} to get the days of the month as a number.
There is a catalogue that I would like to change the to the above sequence - I assume that this is possible within PMP?
Thanks again for help.