Both precision and non-precision, it's a rule of thumb and only suggested. What you actually do is down to the Commander's decision on the day, as long as you're stable by the gate then you can drop the gear whenever suits.

 

Regards,
Ró.

Captain Sim 727-100 has some approach notes in its pdf that is helpful. I've deleted and edited non-general info.

 

APPROACH NOTES

1) Initial pattern entry will normally be in a clean configuration.

4) Normally, the landing gear should not be extended until after at least 5 of flaps have been extended.

 

6) Approaching the glideslope, the pilot flying should call for flaps 25, gear down, flaps 30 (when the gear is down and locked

8) On a visual approach final landing configurations should be established so as to be stabilized no later than 500’ AGL.

For 727 thats true if you dont have any restrictions. Usually you deploying gear at flaps 15. If you need to slow it down really fast - you can use gear as brakes, just dont exceed gear speed limit. Also you will want to be fully configured by 1000 feet AGL. 

 

But in many cases you will have procedure to follow. In that cases you should plan flap and gear extension schedule according to procedure. And again - no procedure will require dangerous maneuvers. So same thing, you will want to be configured at 1000 AGL and stabilized before 500 AGL. Maybe that'll put you into situation where you will intercept Gliseslope at flaps 15, not 25. No problem if you can follow glidepath while reconfiguring aircraft.

 

Gatwick and 727-100 is a good example of tight schedule for flaps and gear. Its almost "on the edge" for 727-100. Tell ATC if you unable to comply. Dont risk. 

 

In EGKK, ILS 08R you should intercept GS at 8.6 nm. You should maintain speed 160 until DME4. Steady flight at 160 KIAS a bit fast for flaps 25. But its normal for gear, and here you should remember about noise Thats why its interesting, to land there 727-100