How do you time a delayed launch?

I've been trying to make a delayed launch like on rocket coasters, but I can't get the trains to; A.Stop once the train hit's the lim's, or B. using brakes to hold the train I can't get the train to just roll into position, it starts to launch and then it gets caught.

Any suggestions? New to NL

What I do is set the brake section slightly larger than the train and then your launch (Transfer) section. On the brakes select "Complete Stop" set it for a few seconds. Then enable your "Transport Device." Set speed for the speed it is coming into the section, NOT the launch speed! Select Launch and set your G preference. Then under "Trigger move the cursor to the right ever so slightly before the line and select "Front Car." That should do it!

huh... I think I get it, gotta try it out. Thanks