Basic TOD point still works with 3 x Altitude = Distance to start TOD from the destination. You may begin descent slightly early but this allows for the slow down to 250kts and then back to flap / gear schedules. Also allows use of partial thrust in descent for gradient changes. Using speed brake latter in descent to fix speed/height problem is more inefficient than a slightly early descent point. Aim for 5000ft @20nm to run at 250kts. Next gate 3000ft @10nm 180kts.
Cheers