| Subject | English | Russian |
| gen. | first and only time | первый и единственный раз (в жизни; you can use it when referring to an occasion when something happened that is likely to not happen again juribt) |
| amer. | first and the only time | первый и последний раз (Val_Ships) |
| gen. | first and the only time | в первый и последний раз (Alex_Odeychuk) |