Which one of the following sounds more natural?
- What is the right time for doing this?
- When is the right time for doing this?
It seems like these both mean the same thing. If they convey different meanings, what is the difference?
Neither sounds natural to me, in the sense that I would say, and would expect to hear, slightly different versions. I'd expect to hear what time... or when should; for example:
Note, this is not to say the phrases in question do not occur; ngrams for What is the right time,When is the right time (or with lower-case w's) clearly shows that they do, with use of the When... form rising steadily since the 1970's. But as shown by ngrams for What is the right time,When is the right time,What time,When should (or with lower-case w's), use of “What time” and “When should” outstrips use of those phrases, perhaps beyond the level attributable to the inherent matching advantage of two-word phrases against five-word phrases.
Also, although I don't know where else it would fit, having “is the right time” plopped down between the first word and the final phrase in the question's examples seems ungainly.