according to news reports, Musk is making moves to establish a STEM-focused K-12 school in Austin. he also wants to open his own University to 'fight illiberalism' on US college campuses.

after his K-12 school opens:

when will he/The Foundation open a University?

similar to the first market above, resolves yes when the opening of a University is objectively on its way: it's legally established, a physical facility (or online curriculum if it's digital-only) exists, it has staff, and is accepting enrolment. school does not need to be in session yet for this market to resolve yes, but it needs to be clear that there aren't major regulatory or practical hurdles to this happening.