The chapter states, 'Use comma after introductory words such as: yes, however, and well.' This implies they should always be used in such cases.
Class 6 › English Grammar and Composition › Chapter 8: Punctuation & Capitalisation › Topic: Comma usage (independent clauses, introductory words, additional information, serial comma, geographical names, dates, addresses, titles)
Aligned to the NCTB national curriculum.