When did Robert ap gwilym ddu write his first poem?

There is no record of a poet named "Robert ap Gwilym Ddu" in Welsh literature.

It's possible you're thinking of the famous Welsh poet Robert ap Gwilym, who lived in the 14th century. He is known for his beautiful and often humorous love poems, but there is no specific information available about when he wrote his first poem.

Could you please double-check the name or provide more context?