As far as I know, both readings are correct, and any native speaker will get them without any issues.
That said, なな is the more common of the spellings, and the default spelling for most words containing 七. しち is only the real no-options-asked spelling for 七月 (しちがつ) or 七時(しちじ)
~~please don’t tell me I am wrong, but if I am, please correct me~~
Both work for just 17. If you wanted to say 17:00 then 十七時 (じゅうしちじ) would be used more often.
2 comments
As far as I know, both readings are correct, and any native speaker will get them without any issues.
That said, なな is the more common of the spellings, and the default spelling for most words containing 七. しち is only the real no-options-asked spelling for 七月
(しちがつ) or 七時(しちじ)
~~please don’t tell me I am wrong, but if I am, please correct me~~
Both work for just 17. If you wanted to say 17:00 then 十七時 (じゅうしちじ) would be used more often.