so to be at 500ft as you roll wings level on final should have you about 1.5nm from touchdown (standard 3deg profile).
A typical single engine trainer with full flap, 60-70 knots and a trickle of power is not a "standard 3 degree profile" by any stretch of the imagination. The three degree profile was put in place for jet transport aircraft where a combination of thrust amount, approach speed and aircraft weight (inertia) meant a rate of descent not exceeding 1000 ft per minute to allow for inertia in the flare.
Of course you can drag a Cessna 150 in with full flap on a estimated three degree glide slope but you will need considerable power to keep the speed up. The normal approach angle for a light single with landing flap, 60-70 knots and 1200 to 1500 rpm is more like five or six degrees and perfectly comfortable. Try flying a PAPI or ILS in a Cessna 150 or Warrior and you will soon discover that significant power is needed to make such a relatively shallow approach if flap is full down.
A three degree approach at 65 knots ground speed gives a rate of descent of 325 feet per minute. Try a 15 knot headwind component and the rate of descent reduces further to 250 fpm. 250 fpm in a Warrior with full flap means an awful lot of power. That means from 500 ft on final it takes you two minutes to the flare. For 140 knots airspeed the rate of descent is around 700 fpm which is omfortable for a 737/A320 allowing for inertia in the flare.
Aiming for a "standard" three degree glide path profile in light aircraft is impractical and unnecessary.