The Sil says that the "Bridge of Menegroth was but 50 leagues distant from the gate of Angband. This is 277.8 kilometres or about 172.5 miles. I'd say that judging by the map of Beleriand that Lammoth is about the same distance away. According to
this essay your height x .415 equals your striding length. Sure, Balrogs are probably different, but maybe that can give us an idea. How tall were Balrogs? Eight, nine feet? More?
If nine feet that means their stride length was 3.735 feet and 1.14 metres. If they stepped once a second (they're kind of hulking) then they would get there in 243,684 seconds or
(drumroll please)
Sixty Seven Hours!
...Okay that was useless.