Professor John B. Polhill writes that there is "probably no great distinction" between XRONOUS and KAIROUS in Acts 1:6, 7 (John B. Polhill, Acts. Nashville, TN: Broadman, 1992).
On the other hand, "XRONOUS refers to the time that must elapse before the establishment of the Kingdom; KAIROUS to the critical events accompanying its establishment" (F.F. Bruce).
At the present time, my view on the semantics of Acts 1:6, 7 vis-a'-vis KAIROS and XRONOS is a neutral one: Polhill indicates that there might be no semantic distinction between the two Greek terms in 1:6, 7. We can't simply base our conclusions on the particular senses of KAIROS and XRONOS in other Scriptures because those occurrences may fit into another semantic domain or context. Maybe if we apply the text-linguistic principles of considering the text (the linguistic unit), co-text (the words in the sentence or phrase being exegeted and, by extension, any texts that have an influence on the exegesis of the text in question) and the context (social and cultural factors), some light could possibly be shed on this problem.