Most 121 FOM's require you to be stabilized at either 500 feet or 1000 feet for a visual approach. This would mean that you need to be established on final at 500 and 1.5 miles from the end of the runway giving a 3 degree glideslope. There are many ways to establish this via VASI/HAT, FMC, etc. etc. The exception would be an approach as TGU, approaching from the south, or River app DCA etc., etc.,.