Nope, no indicator, make note of your launch range, and experience will do the rest (i think it goes active @ 15km)
For any active missile, crank out to the side maintaining lock, watch your RWR, when it resets, the missile is active. Wait unitl it is nearly all lit up again and pull up and in toward the bandit, tapping chaff. make sure you do it for long enough.
neither russian plane can do that. TWS mode can track many targets but not engage like the f15 TWS.