Translation:The next time, I want a meeting in the evening.
Noswaith is a combination of 'Nos' and 'Gwaith' which is 'Night/Evening' and 'Time' (gwaith also means work but this is a completely different meaning)
So a literal meaning of 'Noswaith' is 'Night-time' or 'Evening-time'.
Which is why the greeting 'Noswaith dda' for 'Good evening' is most appropriate ie 'Good Night-time' or 'Good Evening-time'.
Otherwise Nos (or occasionally Noson) is used for evening and night expressions.
Nos Sadwrn = Saturday Night/Evening
Gyda'r nos = In the evening
Nos Galan = New Year's Eve
Bob nos = Every night/evening
Noson Lawen = A merry evening, an expression used to describe an organised get together of performance and fun, less formal than a concert.