There are times when I launch, our squad friggin' rockets straight down instantly and we are far ahead of everyone else. I've done everything trying to reproduce that. For a while I thought it had something to do with pressing (and holding) forwards at the precise time after pressing the launch button, but it's very inconsistent. Happens about 10-20% of the time now and it feels like it can only happen if I spam E to launch at the very start.
On hindsight I think it's because of the squad collision and one of the teams who jumps with us instantly pushes us down, giving us a lot of downwards momentum.