I was able to change an award ticket with UA mile from FRA-ZRH-YUL-ORD-PIT (LX F) to FRA-IAD-PIT (LH418 in F) on June 20 for June 23 flight (saw availability on NH). Really excited to experience the new a/c and F seat!
My strategy these days is to book whatever available (even UA F
) and start checking availability of the desired carrier/flight 2 weeks out.