Since I haven't heard from her, I don't know what time she'll arrive.
Literal
News [subject-が] not-have [because-ので], I [topic-は] she [subject-が] what-time [at-に] arrive [question-か] don't-know.
Embeds the indirect question 何時に着くか (what time she'll arrive) as the object of わからない. Japanese keeps indirect questions as full clauses ending in か, without the English word-order inversion. The ので connects cause (no news) to effect (not knowing).