I know this is a "known issue" but most players have no idea yet. If one does a Vizzy script like:
On Start
Activate Stage
Wait until [fuel stage = 0]
Activate Stage
... both stages will fire simultaneously. This is obviously sub-optimal. As I understand it, the game code does the craft-state calculations after launch, leaving a window wherein all stats are incorrect.
This is easily alleviated by just dropping a [Wait (1) second] block after every [Activate Stage] block. I tested it ~ 20 times on different craft and it seems to work.
Good luck, and fly safe :P