Hidden Conditions
You have to defeat all Ginyu's minions within 10 minutes, including the ones inside their spaceship. After that, you'll get a notification about a new enemy. Head back to the previous area and fly until Burter, Jiece, and Ginyu (possessing Goku's body) intercept you. Take note that sometimes, you have to clear all enemies inside the spaceship first, then go back outside to find more minions. If you defeat them all fast enough, the hidden conditions may still trigger. Defeat the three powered enemies to complete the mission.
Smashed through all friezas henchmen in 4:20 and no ginyu force showed up .....what conditions need to be met to trigger ginyu force arrival ?
It's the unfair RNG (Random Number Generator) system; basically, even if you do fulfill all the conditions needed, there is a chance that it will not activate. You just need to keep doing it.