When starting up JFR with logging, and a delay, something like the following can be seen:
[0.077s][info][jfr] Stack depth set to 128
[0.101s][info][jfr] Global buffer count set to 20
[0.101s][info][jfr] Global buffer size set to 524288
[0.103s][info][jfr] Thread buffer size set to 8192
[0.103s][info][jfr] Memory size set to 10485760
[0.862s][info][jfr] Flight Recorder initialized
[0.862s][info][jfr] Created repository C:\Users\Marcus\AppData\Local\Temp\2018_12_15_15_33_55_67016

The message about the created repo doesn't seem to be corresponding to what the repo location eventually becomes. In my case:
C:\Users\Marcus\AppData\Local\Temp\2018_12_15_15_34_15_67016

The parameters used were:
-Djava.net.preferIPv4Stack=true -XX:+FlightRecorder -XX:FlightRecorderOptions=stackdepth=128 -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints -XX:StartFlightRecording=delay=20s,name=Latency,settings=profile,maxsize=1g -Xlog:jfr=info