Days are built with dydd: dydd Llun is Monday. To say "on Monday" use ar ddydd Llun, with a soft mutation after ar. Months take ym mis: ym mis Mai. Days and months keep their capital letters.
Examples
- Mae gen i ddosbarth ddydd Mercher.
- I have a class on Wednesday.
- Ym mis Ebrill dw i'n mynd i Fiena.
- In April I'm going to Vienna.
- Dydd Sadwrn dw i ddim yn gweithio.
- On Saturday I don't work.
The mistake to avoid
Ar causes a soft mutation, so dydd becomes ddydd.
Where this fits in
Numbers, days, time, Welsh A1: Count, talk about days and months, give the time, and handle numbers in real situations.