There is a lot of mathematical literatur in some non-English languages (French, German, Spanish, etc.) that students from these countries don't need to read English literature (at least) for their undergraduate studies. However, in more advanced classes or when a student wants to get closer to research, there is mostly only English literature, i.e., at some point he/she has to start reading mathematical literature written in English.

When should a student be encouraged to read mathematical literature written in English? Why?

(I'm beware that this is not a big problem in countries where there is rarely any native literature.)