did you see that : when chkdsk is doing stage 1 then the time is going down...stage 2 the timer counts up i found that using /f /v /x /sdcleanup parameters with a console during install , did not tried others settings yet
Chkdsk of Windows 8.1 gave me 1 second to press anykey. on Windows 10TP it gives me 8 seconds. However, due to a ctrl button glitch. chkdsk of startup never works for me